Incorrect property values in Get-AzPrivateDnsZone cmdlet results

## Description
We've had reports from a customer of late about the `NumberOfVirtualNetworkLinks` property having incorrect values when executed without `-Name` and `-ResourceGroupName` parameters.

## Steps to reproduce
- Run `Get-AzPrivateDnsZone` with and without `-ResourceGroup` and `-Name` parameters and note the difference in output.

`NumberOfVirtualNetworkLinks` property in `Get-AzPrivateDnsZone` cmdlet output seems to always show `0` (incorrect value), even when there are linked VNets. Correct value reflects only when `-ResourceGroup` and `-Name` parameters are passed along.

**Findings:** The `Get-AzPrivateDnsZone` and `Get-AzPrivateDnsZone -ResourceGroupName ` commands apparently invoke the [Private Zones - List](https://docs.microsoft.com/en-us/rest/api/dns/privatedns/private-zones/list) and [Private Zones - List By Resource Group](https://docs.microsoft.com/en-us/rest/api/dns/privatedns/private-zones/list-by-resource-group) ​REST APIs under the hood, that has the `NumberOfVirtualNetworkLinks` property set to `0` in the response. Whereas, `Get-AzPrivateDnsZone -ResourceGroupName -Name ` command calls the [Private Zones - Get](https://docs.microsoft.com/en-us/rest/api/dns/privatedns/private-zones/get) REST API that populates the `NumberOfVirtualNetworkLinks` property as well with the appropriate value.

**Post:** [Property 'NumberOfVirtualNetworkLinks' not reported #1885](https://github.com/MicrosoftDocs/azure-docs-powershell/issues/1885)

**Workaround:**
To work around this behavior, one has to run the `Get-AzPrivateDnsZone` cmdlet **twice** to obtain the extended properties, as follows:
```
$AllPrivateDnsZones = Get-AzPrivateDnsZone
$AllPrivateDnsZonesExtended = @()

foreach($PrivateDnsZone in $AllPrivateDnsZones)
{
$PrivateDnsZoneExtended = Get-AzPrivateDnsZone -ResourceGroupName $PrivateDnsZone.ResourceGroupName -Name $PrivateDnsZone.Name
$AllPrivateDnsZonesExtended += $PrivateDnsZoneExtended
}

$AllPrivateDnsZonesExtended | ft -Property Name, ResourceGroupName, NumberOfVirtualNetworkLinks
```

**Ask:** IMHO, this experience can confuse customers especially when they're new to using Azure PowerShell modules/cmdlets to manage their resources and mislead them when such data discrepancies are observed. Would love to know your thoughts on the expected behavior and how this experience can be improved.

## Environment data

```
Name Value
---- -----
PSVersion 7.1.4
PSEdition Core
GitCommitId 7.1.4
OS Microsoft Windows 10.0.19043
Platform Win32NT
PSCompatibleVersions {1.0, 2.0, 3.0, 4.0…}
PSRemotingProtocolVersion 2.3
SerializationVersion 1.1.0.1
WSManStackVersion 3.0
```

## Module versions

```powershell
ModuleType Version PreRelease Name PSEdition ExportedCommands
---------- ------- ---------- ---- --------- ----------------
Script 6.0.0 Az Core,Desk
Script 2.3.0 Az.Accounts Core,Desk {Disable-AzDataCollection, Disable-AzContextAutosave, Enable-AzDataCollection, Enable-AzContextAutosave…}
Script 1.7.5 Az.Accounts Core,Desk {Disable-AzDataCollection, Disable-AzContextAutosave, Enable-AzDataCollection, Enable-AzContextAutosave…}
Script 1.7.0 Az.Accounts Core,Desk {Disable-AzDataCollection, Disable-AzContextAutosave, Enable-AzDataCollection, Enable-AzContextAutosave…}
Script 1.1.1 Az.Advisor Core,Desk {Get-AzAdvisorRecommendation, Enable-AzAdvisorRecommendation, Disable-AzAdvisorRecommendation, Get-AzAdvisorConfiguration…}
Script 2.1.0 Az.Aks Core,Desk {Get-AzAksCluster, New-AzAksCluster, Remove-AzAksCluster, Import-AzAksCredential…}
Script 1.0.3 Az.Aks Core,Desk {Get-AzAks, New-AzAks, Remove-AzAks, Import-AzAksCredential…}
Script 0.2.0 Az.AlertsManagement Core,Desk {Get-AzAlert, Get-AzAlertObjectHistory, Update-AzAlertState, Measure-AzAlertStatistic…}
Script 1.1.4 Az.AnalysisServices Core,Desk {Resume-AzAnalysisServicesServer, Suspend-AzAnalysisServicesServer, Get-AzAnalysisServicesServer, Remove-AzAnalysisService…
Script 1.1.2 Az.AnalysisServices Core,Desk {Resume-AzAnalysisServicesServer, Suspend-AzAnalysisServicesServer, Get-AzAnalysisServicesServer, Remove-AzAnalysisService…
Script 2.2.0 Az.ApiManagement Core,Desk {Add-AzApiManagementApiToGateway, Add-AzApiManagementApiToProduct, Add-AzApiManagementProductToGroup, Add-AzApiManagementR…
Script 1.4.1 Az.ApiManagement Core,Desk {Add-AzApiManagementApiToProduct, Add-AzApiManagementProductToGroup, Add-AzApiManagementRegion, Add-AzApiManagementUserToG…
Script 1.3.3 Az.ApiManagement Core,Desk {Add-AzApiManagementApiToProduct, Add-AzApiManagementProductToGroup, Add-AzApiManagementRegion, Add-AzApiManagementUserToG…
Script 1.0.0 Az.AppConfiguration Core,Desk {Get-AzAppConfigurationStore, Get-AzAppConfigurationStoreKey, New-AzAppConfigurationStore, New-AzAppConfigurationStoreKey…}
Script 1.1.0 Az.ApplicationInsights Core,Desk {Get-AzApplicationInsights, New-AzApplicationInsights, Remove-AzApplicationInsights, Update-AzApplicationInsights…}
Script 1.0.3 Az.ApplicationInsights Core,Desk {Get-AzApplicationInsights, New-AzApplicationInsights, Remove-AzApplicationInsights, Set-AzApplicationInsightsPricingPlan…}
Script 1.7.0 Az.Automation Core,Desk {Get-AzAutomationHybridWorkerGroup, Remove-AzAutomationHybridWorkerGroup, Get-AzAutomationJobOutputRecord, Import-AzAutoma…
Script 1.3.6 Az.Automation Core,Desk {Get-AzAutomationHybridWorkerGroup, Remove-AzAutomationHybridWorkerGroup, Get-AzAutomationJobOutputRecord, Import-AzAutoma…
Script 1.3.5 Az.Automation Core,Desk {Get-AzAutomationHybridWorkerGroup, Remove-AzAutomationHybridWorkerGroup, Get-AzAutomationJobOutputRecord, Import-AzAutoma…
Script 3.1.0 Az.Batch Core,Desk {Remove-AzBatchAccount, Get-AzBatchAccount, Get-AzBatchAccountKey, New-AzBatchAccount…}
Script 2.0.2 Az.Batch Core,Desk {Remove-AzBatchAccount, Get-AzBatchAccount, Get-AzBatchAccountKey, New-AzBatchAccount…}
Script 2.0.0 Az.Billing Core,Desk {Get-AzBillingInvoice, Get-AzBillingPeriod, Get-AzEnrollmentAccount, Get-AzConsumptionBudget…}
Script 1.0.2 Az.Billing Core,Desk {Get-AzBillingInvoice, Get-AzBillingPeriod, Get-AzEnrollmentAccount, Get-AzConsumptionBudget…}
Script 1.7.0 Az.Cdn Core,Desk {Get-AzCdnProfile, Get-AzCdnProfileSsoUrl, New-AzCdnProfile, Remove-AzCdnProfile…}
Script 1.4.2 Az.Cdn Core,Desk {Get-AzCdnProfile, Get-AzCdnProfileSsoUrl, New-AzCdnProfile, Remove-AzCdnProfile…}
Script 1.8.0 Az.CognitiveServices Core,Desk {Get-AzCognitiveServicesAccount, Get-AzCognitiveServicesAccountKey, Get-AzCognitiveServicesAccountSku, Get-AzCognitiveServ…
Script 1.3.0 Az.CognitiveServices Core,Desk {Get-AzCognitiveServicesAccount, Get-AzCognitiveServicesAccountKey, Get-AzCognitiveServicesAccountSku, Get-AzCognitiveServ…
Script 1.2.2 Az.CognitiveServices Core,Desk {Get-AzCognitiveServicesAccount, Get-AzCognitiveServicesAccountKey, Get-AzCognitiveServicesAccountSku, Get-AzCognitiveServ…
Script 4.13.0 Az.Compute Core,Desk {Remove-AzAvailabilitySet, Get-AzAvailabilitySet, New-AzAvailabilitySet, Update-AzAvailabilitySet…}
Script 3.7.0 Az.Compute Core,Desk {Remove-AzAvailabilitySet, Get-AzAvailabilitySet, New-AzAvailabilitySet, Update-AzAvailabilitySet…}
Script 2.0.0 Az.ContainerInstance Core,Desk {Add-AzContainerInstanceOutput, Get-AzContainerGroup, Get-AzContainerInstanceCachedImage, Get-AzContainerInstanceCapabilit…
Script 2.2.3 Az.ContainerRegistry Core,Desk {New-AzContainerRegistry, Get-AzContainerRegistry, Update-AzContainerRegistry, Remove-AzContainerRegistry…}
Script 1.2.0 Az.CosmosDB Core,Desk {Get-AzCosmosDBSqlContainer, Get-AzCosmosDBSqlContainerThroughput, Get-AzCosmosDBSqlDatabase, Get-AzCosmosDBSqlDatabaseThr…
Script 1.1.0 Az.DataBoxEdge Core,Desk {Get-AzDataBoxEdgeJob, Get-AzDataBoxEdgeDevice, Invoke-AzDataBoxEdgeDevice, New-AzDataBoxEdgeDevice…}
Script 1.1.0 Az.Databricks Core,Desk {Get-AzDatabricksVNetPeering, Get-AzDatabricksWorkspace, New-AzDatabricksVNetPeering, New-AzDatabricksWorkspace…}
Script 1.12.0 Az.DataFactory Core,Desk {Set-AzDataFactoryV2, Update-AzDataFactoryV2, Get-AzDataFactoryV2, Remove-AzDataFactoryV2…}
Script 1.7.0 Az.DataFactory Core,Desk {Set-AzDataFactoryV2, Update-AzDataFactoryV2, Get-AzDataFactoryV2, Remove-AzDataFactoryV2…}
Script 1.6.0 Az.DataFactory Core,Desk {Set-AzDataFactoryV2, Update-AzDataFactoryV2, Get-AzDataFactoryV2, Remove-AzDataFactoryV2…}
Script 1.2.6 Az.DataLakeStore Core,Desk {Get-AzDataLakeStoreTrustedIdProvider, Remove-AzDataLakeStoreTrustedIdProvider, Remove-AzDataLakeStoreFirewallRule, Set-Az…
Script 1.0.2 Az.DeploymentManager Core,Desk {Get-AzDeploymentManagerArtifactSource, New-AzDeploymentManagerArtifactSource, Set-AzDeploymentManagerArtifactSource, Remo…
Script 3.0.0 Az.DesktopVirtualization Core,Desk {Disconnect-AzWvdUserSession, Expand-AzWvdMsixImage, Get-AzWvdApplication, Get-AzWvdApplicationGroup…}
Script 1.2.3 Az.EventGrid Core,Desk {New-AzEventGridTopic, Get-AzEventGridTopic, Set-AzEventGridTopic, New-AzEventGridTopicKey…}
Script 1.4.3 Az.EventHub Core,Desk {New-AzEventHubNamespace, Get-AzEventHubNamespace, Set-AzEventHubNamespace, Remove-AzEventHubNamespace…}
Script 1.8.0 Az.FrontDoor Core,Desk {New-AzFrontDoor, Get-AzFrontDoor, Set-AzFrontDoor, Remove-AzFrontDoor…}
Script 1.4.0 Az.FrontDoor Core,Desk {New-AzFrontDoor, Get-AzFrontDoor, Set-AzFrontDoor, Remove-AzFrontDoor…}
Script 1.3.0 Az.FrontDoor Core,Desk {New-AzFrontDoor, Get-AzFrontDoor, Set-AzFrontDoor, Remove-AzFrontDoor…}
Script 3.0.0 Az.Functions Core,Desk {Get-AzFunctionApp, Get-AzFunctionAppAvailableLocation, Get-AzFunctionAppPlan, Get-AzFunctionAppSetting…}
Script 3.1.0 Az.HDInsight Core,Desk {Get-AzHDInsightJob, New-AzHDInsightSqoopJobDefinition, Wait-AzHDInsightJob, New-AzHDInsightStreamingMapReduceJobDefinitio…
Script 3.0.2 Az.HDInsight Core,Desk {Get-AzHDInsightJob, New-AzHDInsightSqoopJobDefinition, Wait-AzHDInsightJob, New-AzHDInsightStreamingMapReduceJobDefinitio…
Script 1.0.1 Az.HealthcareApis Core,Desk {New-AzHealthcareApisService, Remove-AzHealthcareApisService, Set-AzHealthcareApisService, Get-AzHealthcareApisService}
Script 2.4.0 Az.IotHub Core,Desk {Add-AzIotHubKey, Get-AzIotHubEventHubConsumerGroup, Get-AzIotHubConnectionString, Get-AzIotHubJob…}
Script 2.0.1 Az.IotHub Core,Desk {Add-AzIotHubKey, Get-AzIotHubEventHubConsumerGroup, Get-AzIotHubConnectionString, Get-AzIotHubJob…}
Script 3.4.4 Az.KeyVault Core,Desk {Add-AzKeyVaultCertificate, Update-AzKeyVaultCertificate, Stop-AzKeyVaultCertificateOperation, Get-AzKeyVaultCertificateOp…
Script 1.6.0 Az.KeyVault Core,Desk {Add-AzKeyVaultCertificate, Update-AzKeyVaultCertificate, Stop-AzKeyVaultCertificateOperation, Get-AzKeyVaultCertificateOp…
Script 1.4.0 Az.KeyVault Core,Desk {Add-AzKeyVaultCertificate, Update-AzKeyVaultCertificate, Stop-AzKeyVaultCertificateOperation, Get-AzKeyVaultCertificateOp…
Script 2.0.0 Az.Kusto Core,Desk {Add-AzKustoClusterLanguageExtension, Add-AzKustoDatabasePrincipal, Get-AzKustoAttachedDatabaseConfiguration, Get-AzKustoC…
Script 1.1.1 Az.Maintenance Core,Desk {Get-AzApplyUpdate, Get-AzConfigurationAssignment, Get-AzMaintenanceConfiguration, Get-AzMaintenanceUpdate…}
Script 1.0.0 Az.Maintenance Core,Desk {Get-AzApplyUpdate, Get-AzConfigurationAssignment, Get-AzMaintenanceConfiguration, Get-AzMaintenanceUpdate…}
Script 1.0.2 Az.ManagedServices Core,Desk {Get-AzManagedServicesAssignment, New-AzManagedServicesAssignment, Remove-AzManagedServicesAssignment, Get-AzManagedServic…
Script 1.0.2 Az.Migrate Core,Desk {Get-AzMigrateDiscoveredServer, Get-AzMigrateJob, Get-AzMigrateProject, Get-AzMigrateReplicationFabric…}
Script 1.7.0 Az.Monitor Core,Desk {Get-AzMetricDefinition, Get-AzMetric, Remove-AzLogProfile, Get-AzLogProfile…}
Script 1.5.0 Az.Monitor Core,Desk {Get-AzMetricDefinition, Get-AzMetric, Remove-AzLogProfile, Get-AzLogProfile…}
Script 4.8.0 Az.Network Core,Desk {Add-AzApplicationGatewayAuthenticationCertificate, Get-AzApplicationGatewayAuthenticationCertificate, New-AzApplicationGa…
Script 2.5.0 Az.Network Core,Desk {Add-AzApplicationGatewayAuthenticationCertificate, Get-AzApplicationGatewayAuthenticationCertificate, New-AzApplicationGa…
Script 2.2.1 Az.Network Core,Desk {Add-AzApplicationGatewayAuthenticationCertificate, Get-AzApplicationGatewayAuthenticationCertificate, New-AzApplicationGa…
Script 1.3.4 Az.OperationalInsights Core,Desk {New-AzOperationalInsightsAzureActivityLogDataSource, New-AzOperationalInsightsCustomLogDataSource, Disable-AzOperationalI…
Script 1.3.0 Az.PolicyInsights Core,Desk {Get-AzPolicyEvent, Get-AzPolicyState, Get-AzPolicyStateSummary, Get-AzPolicyRemediation…}
Script 1.1.4 Az.PolicyInsights Core,Desk {Get-AzPolicyEvent, Get-AzPolicyState, Get-AzPolicyStateSummary, Get-AzPolicyRemediation…}
Script 0.1.0 Az.Portal Core,Desk {Get-AzPortalDashboard, New-AzPortalDashboard, Remove-AzPortalDashboard, Set-AzPortalDashboard…}
Script 1.1.1 Az.PowerBIEmbedded Core,Desk {Remove-AzPowerBIWorkspaceCollection, Get-AzPowerBIWorkspaceCollection, Get-AzPowerBIWorkspaceCollectionAccessKey, Get-AzP…
Script 1.0.2 Az.PrivateDns Core,Desk {Get-AzPrivateDnsZone, Remove-AzPrivateDnsZone, Set-AzPrivateDnsZone, New-AzPrivateDnsZone…}
Script 4.1.0 Az.RecoveryServices Core,Desk {Get-AzRecoveryServicesBackupProperty, Get-AzRecoveryServicesVault, Get-AzRecoveryServicesVaultSettingsFile, New-AzRecover…
Script 2.8.0 Az.RecoveryServices Core,Desk {Get-AzRecoveryServicesBackupProperty, Get-AzRecoveryServicesVault, Get-AzRecoveryServicesVaultSettingsFile, New-AzRecover…
Script 2.4.0 Az.RecoveryServices Core,Desk {Get-AzRecoveryServicesBackupProperty, Get-AzRecoveryServicesVault, Get-AzRecoveryServicesVaultSettingsFile, New-AzRecover…
Script 1.0.0 Az.ResourceMover Core,Desk {Add-AzResourceMoverMoveResource, Get-AzResourceMoverMoveCollection, Get-AzResourceMoverMoveResource, Get-AzResourceMoverR…
Script 4.1.0 Az.Resources Core,Desk {Get-AzProviderOperation, Remove-AzRoleAssignment, Get-AzRoleAssignment, New-AzRoleAssignment…}
Script 1.13.0 Az.Resources Core,Desk {Get-AzProviderOperation, Remove-AzRoleAssignment, Get-AzRoleAssignment, New-AzRoleAssignment…}
Script 1.9.1 Az.Resources Core,Desk {Get-AzProviderOperation, Remove-AzRoleAssignment, Get-AzRoleAssignment, New-AzRoleAssignment…}
Script 1.0.0 Az.SecurityInsights Core,Desk {Get-AzSentinelAlertRuleAction, New-AzSentinelAlertRuleAction, Remove-AzSentinelAlertRuleAction, Update-AzSentinelAlertRul…
Script 3.0.0 Az.ServiceFabric Core,Desk {Add-AzServiceFabricClientCertificate, Add-AzServiceFabricNode, Add-AzServiceFabricNodeType, Get-AzServiceFabricCluster…}
Script 2.0.2 Az.ServiceFabric Core,Desk {Add-AzServiceFabricClientCertificate, Add-AzServiceFabricClusterCertificate, Add-AzServiceFabricNode, Add-AzServiceFabric…
Script 2.0.1 Az.ServiceFabric Core,Desk {Add-AzServiceFabricClientCertificate, Add-AzServiceFabricClusterCertificate, Add-AzServiceFabricNode, Add-AzServiceFabric…
Script 1.1.1 Az.SignalR Core,Desk {New-AzSignalR, Get-AzSignalR, Get-AzSignalRKey, New-AzSignalRKey…}
Script 3.1.0 Az.Sql Core,Desk {Get-AzSqlDatabaseTransparentDataEncryption, Get-AzSqlDatabaseTransparentDataEncryptionActivity, Set-AzSqlDatabaseTranspar…
Script 2.6.0 Az.Sql Core,Desk {Get-AzSqlDatabaseTransparentDataEncryption, Get-AzSqlDatabaseTransparentDataEncryptionActivity, Set-AzSqlDatabaseTranspar…
Script 2.1.2 Az.Sql Core,Desk {Get-AzSqlDatabaseTransparentDataEncryption, Get-AzSqlDatabaseTransparentDataEncryptionActivity, Set-AzSqlDatabaseTranspar…
Script 1.0.2 Az.SqlVirtualMachine Core,Desk {New-AzSqlVM, Get-AzSqlVM, Update-AzSqlVM, Remove-AzSqlVM…}
Script 3.7.0 Az.Storage Core,Desk {Get-AzStorageAccount, Get-AzStorageAccountKey, New-AzStorageAccount, New-AzStorageAccountKey…}
Script 1.14.0 Az.Storage Core,Desk {Get-AzStorageAccount, Get-AzStorageAccountKey, New-AzStorageAccount, New-AzStorageAccountKey…}
Script 1.11.0 Az.Storage Core,Desk {Get-AzStorageAccount, Get-AzStorageAccountKey, New-AzStorageAccount, New-AzStorageAccountKey…}
Script 1.5.0 Az.StorageSync Core,Desk {Invoke-AzStorageSyncCompatibilityCheck, New-AzStorageSyncService, Get-AzStorageSyncService, Set-AzStorageSyncService…}
Script 1.2.3 Az.StorageSync Core,Desk {Invoke-AzStorageSyncCompatibilityCheck, New-AzStorageSyncService, Get-AzStorageSyncService, Remove-AzStorageSyncService…}
Script 1.2.2 Az.StorageSync Core,Desk {Invoke-AzStorageSyncCompatibilityCheck, New-AzStorageSyncService, Get-AzStorageSyncService, Remove-AzStorageSyncService…}
Script 2.0.0 Az.StreamAnalytics Core,Desk {Get-AzStreamAnalyticsCluster, Get-AzStreamAnalyticsClusterStreamingJob, Get-AzStreamAnalyticsDefaultFunctionDefinition, G…
Script 1.0.3 Az.TrafficManager Core,Desk {Add-AzTrafficManagerCustomHeaderToEndpoint, Remove-AzTrafficManagerCustomHeaderFromEndpoint, Add-AzTrafficManagerCustomHe…
Script 2.6.0 Az.Websites Core,Desk {Get-AzAppServicePlan, Set-AzAppServicePlan, New-AzAppServicePlan, Remove-AzAppServicePlan…}
Script 1.8.0 Az.Websites Core,Desk {Get-AzAppServicePlan, Set-AzAppServicePlan, New-AzAppServicePlan, Remove-AzAppServicePlan…}
Script 1.5.1 Az.Websites Core,Desk {Get-AzAppServicePlan, Set-AzAppServicePlan, New-AzAppServicePlan, Remove-AzAppServicePlan…}
Binary 1.2.1026 MicrosoftPowerBIMgmt.Data Desk {Add-PowerBIDataset, Set-PowerBITable, New-PowerBIDataset, New-PowerBITable…}
Binary 1.2.1026 MicrosoftPowerBIMgmt.Profile Desk {Connect-PowerBIServiceAccount, Disconnect-PowerBIServiceAccount, Invoke-PowerBIRestMethod, Get-PowerBIAccessToken…}
Binary 1.2.1026 MicrosoftPowerBIMgmt.Reports Desk {Get-PowerBIReport, New-PowerBIReport, Export-PowerBIReport, Get-PowerBIDashboard…}
Script 1.4.6 PackageManagement Desk {Find-Package, Get-Package, Get-PackageProvider, Get-PackageSource…}
Script 2.2.3 PowerShellGet Desk {Find-Command, Find-DSCResource, Find-Module, Find-RoleCapability…}
```