whatIf breaks on Microsoft.Network/privateEndpoints/privateDnsZoneGroups

**Describe the bug**
Trying to do WhatIf on a deployment of Microsoft.Network/privateEndpoints/privateDnsZoneGroups failes with the following error:
```
An error occurred while deploying this offering. Error:
DeploymentWhatIfResourceInvalidResponse - Long running
operation failed with status 'Failed'. Additional Info:'The
request to predict template deployment changes to scope
'/subscriptions/1c914d97-9725-4deb-b857-269c4c416949' has
failed due to missing or unexpected response on request
'/subscriptions/1c914d97-9725-4deb-b857-269c4c416949/resourceGroups/acc-vnet-rg/providers/Microsoft.Network/privateEndpoints/privateEndpoint-michiel20210903-Blob/privateDnsZoneGroups/default?api-version=2021-05-01'. Diagnostic information: timestamp '20220712T071310Z', tracking id 'c1446b9b-35de-4018-ac86-ef2585e06c6f', request correlation id '6310f502-8211-47c0-a07f-5e889d26c7de', location 'westeurope'.'
```

The deployment itself succeeds completely and results in the requested resources being created, so this seems to be an issue in the handling of WhatIf in this resource type.

**To Reproduce**
Steps to reproduce the behavior:
Use the following Bicep template to deploy a private dns zone config to a private endpoint:
```
param dnsConfig object
param privateEndpointName string

resource privateEndpoint 'Microsoft.Network/privateEndpoints@2022-01-01' existing = {
name: privateEndpointName
}

resource privateDnsZone 'Microsoft.Network/privateDnsZones@2020-06-01' existing = {
name: dnsConfig.name
scope: resourceGroup(dnsConfig.subscriptionId, dnsConfig.resourceGroup)
}

resource dnsZoneConfig 'Microsoft.Network/privateEndpoints/privateDnsZoneGroups@2021-05-01' = {
name: 'default'
parent: privateEndpoint
properties: {
privateDnsZoneConfigs: [
{
name: replace(dnsConfig.name, '.', '-')
properties: {
privateDnsZoneId: privateDnsZone.id
}
}
]
}
}
```

The config used is as follows:
```
{
"$schema": "https://schema.management.azure.com/schemas/2015-01-01/deploymentParameters.json#",
"contentVersion": "1.0.0.0",
"parameters": {
"dnsConfig": {
"value": {
"subscriptionId": "1c914d97-9725-4deb-b857-269c4c416949",
"resourceGroup": "michieltest",
"name": "privatelink.blob.core.windows.net"
}
},
"privateEndpointName": {
"value": "privateEndpoint-michiel20210903-Blob"
}
}
}
```

The private endpoint resource's properties are as follows:
```
{
"name": "privateEndpoint-michiel20210903-Blob",
"type": "Microsoft.Network/privateEndpoints",
"location": "westeurope",
"properties": {
"privateLinkServiceConnections": [
{
"name": "serviceConnection-michiel20210903-Blob",
"properties": {
"provisioningState": "Succeeded",
"privateLinkServiceId": "/subscriptions/1c914d97-9725-4deb-b857-269c4c416949/resourceGroups/michieltest/providers/Microsoft.Storage/storageAccounts/michiel20210903",
"groupIds": [
"Blob"
],
"requestMessage": "AutoApproved",
"privateLinkServiceConnectionState": {
"status": "Approved",
"description": "Auto-Approved"
}
}
}
],
"subnet": {
"id": "/subscriptions/1c914d97-9725-4deb-b857-269c4c416949/resourceGroups/acc-vnet-rg/providers/Microsoft.Network/virtualNetworks/acc001-vnet/subnets/globaludr001a-subnet"
}
}
}
```

**Expected behavior**
A WhatIf output of the changes that the deployment entices

**Client**
PowerShell

**Additional context**
Add any other context about the problem here.

Start by reproducing WhatIf with the provided Bicep template, deployment parameters, and Microsoft.Network/privateEndpoints/privateDnsZoneGroups resource. Compare the successful deployment with the failed WhatIf response and investigate handling of the 2021-05-01 privateDnsZoneGroups API response; done means WhatIf reports the expected deployment changes without the invalid-response error.

Written by the indexing model from the issue text.