`Microsoft.Insights/diagnosticSettings@2021-05-01-preview` - `logAnalyticsDestinationType` break PUT-GET consistency

## Background
Under some situation when set `logAnalyticsDestinationType` as `Dedicated`, the API returns `null`, and when set `logAnalyticsDestinationType` as `null` (or not set), the API returns `AzureDiagnostics`. This breaks PUT-GET consistency, see [roundtrip_inconsistent_property](https://github.com/Azure/azure-rest-api-specs/blob/main/documentation/Semantic-and-Model-Violations-Reference.md#roundtrip_inconsistent_property). The diagnostic setting can be used for many target resource, it is hard to fully test all the situation. Below shows two cases:
1. target KeyVault, PUT `AzureDiagnostics` or `Dedicated`, GET `null`
2. target DataFactory (V2), PUT `null`, GET `AzureDiagnostics`. But PUT `AzureDiagnostics` or `Dedicated` can work well.

## swagger:
https://github.com/Azure/azure-rest-api-specs/blob/e0a8a42064db5ad298a3f660805d65283c07aca2/specification/monitor/resource-manager/Microsoft.Insights/preview/2021-05-01-preview/diagnosticsSettings_API.json#L323-L327

## API flow 1, target KeyVault, PUT `AzureDiagnostics` or `Dedicated`, GET `null`
PUT https://management.azure.com/subscriptions/XXXX/resourceGroups/wt-diagnostic-resources/providers/Microsoft.KeyVault/vaults/wtexpkeyvault/providers/microsoft.insights/diagnosticSettings/exp?api-version=2021-05-01-preview
x-ms-request-id: 34a48570-6b21-49fd-af95-f611c88ec97f
x-ms-correlation-request-id: 04fe903c-847d-427c-b23b-9ed8c53966b9

payload

```json
{
"properties": {
"logs": [
{
"category": "AuditEvent",
"categoryGroup": null,
"enabled": true,
"retentionPolicy": {
"days": 0,
"enabled": false
}
},
{
"category": "AzurePolicyEvaluationDetails",
"categoryGroup": null,
"enabled": false,
"retentionPolicy": {
"days": 0,
"enabled": false
}
}
],
"metrics": [
{
"timeGrain": null,
"enabled": true,
"retentionPolicy": {
"days": 0,
"enabled": false
},
"category": "AllMetrics"
}
],
"workspaceId": "/subscriptions/XXXX/resourceGroups/wt-diagnostic-resources/providers/Microsoft.OperationalInsights/workspaces/wt-testlaw",
"logAnalyticsDestinationType": "AzureDiagnostics"
}
}
```
200 OK
```json
{
"id": "/subscriptions/XXXX/resourcegroups/wt-diagnostic-resources/providers/microsoft.keyvault/vaults/wtexpkeyvault/providers/microsoft.insights/diagnosticSettings/exp",
"type": "Microsoft.Insights/diagnosticSettings",
"name": "exp",
"location": null,
"kind": null,
"tags": null,
"properties": {
"storageAccountId": null,
"serviceBusRuleId": null,
"workspaceId": "/subscriptions/XXXX/resourceGroups/wt-diagnostic-resources/providers/Microsoft.OperationalInsights/workspaces/wt-testlaw",
"eventHubAuthorizationRuleId": null,
"eventHubName": null,
"metrics": [
{
"timeGrain": "PT1M",
"category": "AllMetrics",
"enabled": true,
"retentionPolicy": {
"enabled": false,
"days": 0
}
}
],
"logs": [
{
"category": "AuditEvent",
"categoryGroup": null,
"enabled": true,
"retentionPolicy": {
"enabled": false,
"days": 0
}
},
{
"category": "AzurePolicyEvaluationDetails",
"categoryGroup": null,
"enabled": false,
"retentionPolicy": {
"enabled": false,
"days": 0
}
}
],
"logAnalyticsDestinationType": "AzureDiagnostics"
},
"identity": null
}
```

---

GET https://management.azure.com/subscriptions/XXXX/resourceGroups/wt-diagnostic-resources/providers/Microsoft.KeyVault/vaults/wtexpkeyvault/providers/microsoft.insights/diagnosticSettings/exp?api-version=2021-05-01-preview
x-ms-request-id: 1cb12d3e-463e-4a4d-9a8c-d1c963a2c4e3
x-ms-correlation-request-id: f430d3e4-c539-4cc5-b4be-78d3585e7322
200 OK

payload

```json
{
"id": "/subscriptions/XXXX/resourcegroups/wt-diagnostic-resources/providers/microsoft.keyvault/vaults/wtexpkeyvault/providers/microsoft.insights/diagnosticSettings/exp",
"type": "Microsoft.Insights/diagnosticSettings",
"name": "exp",
"location": null,
"kind": null,
"tags": null,
"properties": {
"storageAccountId": null,
"serviceBusRuleId": null,
"workspaceId": "/subscriptions/XXXX/resourceGroups/wt-diagnostic-resources/providers/Microsoft.OperationalInsights/workspaces/wt-testlaw",
"eventHubAuthorizationRuleId": null,
"eventHubName": null,
"metrics": [
{
"category": "AllMetrics",
"enabled": true,
"retentionPolicy": {
"enabled": false,
"days": 0
}
}
],
"logs": [
{
"category": "AuditEvent",
"categoryGroup": null,
"enabled": true,
"retentionPolicy": {
"enabled": false,
"days": 0
}
},
{
"category": "AzurePolicyEvaluationDetails",
"categoryGroup": null,
"enabled": false,
"retentionPolicy": {
"enabled": false,
"days": 0
}
}
],
"logAnalyticsDestinationType": null
},
"identity": null
}
```

## API flow 2, target DataFactory (V2), PUT `null`, GET `AzureDiagnostics`. But PUT `AzureDiagnostics` or `Dedicated` can work well
PUT https://management.azure.com/subscriptions/XXXX/resourceGroups/wt-diagnostic-resources/providers/Microsoft.DataFactory/factories/wt-acctest/providers/microsoft.insights/diagnosticSettings/wt-datafac-DS?api-version=2021-05-01-preview
x-ms-request-id: d738f84e-cf08-449a-a370-7b328ed7e3bd
x-ms-correlation-request-id: f65996b6-3bf5-492f-bf1c-b6a7734d8bdd

payload

```json
{
"properties": {
"logs": [
{
"category": "SSISIntegrationRuntimeLogs",
"categoryGroup": null,
"enabled": true,
"retentionPolicy": {
"days": 0,
"enabled": false
}
}
],
"metrics": [
{
"timeGrain": null,
"enabled": false,
"retentionPolicy": {
"days": 0,
"enabled": false
},
"category": "AllMetrics"
}
],
"workspaceId": "/subscriptions/XXXX/resourceGroups/wt-diagnostic-resources/providers/Microsoft.OperationalInsights/workspaces/wt-testlaw",
"logAnalyticsDestinationType": ""
}
}
```
200 OK
```json
{
"id": "/subscriptions/XXXX/resourcegroups/wt-diagnostic-resources/providers/microsoft.datafactory/factories/wt-acctest/providers/microsoft.insights/diagnosticSettings/wt-datafac-DS",
"type": "Microsoft.Insights/diagnosticSettings",
"name": "wt-datafac-DS",
"location": null,
"kind": null,
"tags": null,
"properties": {
"storageAccountId": null,
"serviceBusRuleId": null,
"workspaceId": "/subscriptions/XXXX/resourceGroups/wt-diagnostic-resources/providers/Microsoft.OperationalInsights/workspaces/wt-testlaw",
"eventHubAuthorizationRuleId": null,
"eventHubName": null,
"metrics": [
{
"timeGrain": "PT1M",
"category": "AllMetrics",
"enabled": false,
"retentionPolicy": {
"enabled": false,
"days": 0
}
}
],
"logs": [
{
"category": "SSISIntegrationRuntimeLogs",
"categoryGroup": null,
"enabled": true,
"retentionPolicy": {
"enabled": false,
"days": 0
}
}
],
"logAnalyticsDestinationType": ""
},
"identity": null
}
```

---

GET https://management.azure.com/subscriptions/XXXX/resourceGroups/wt-diagnostic-resources/providers/Microsoft.DataFactory/factories/wt-acctest/providers/microsoft.insights/diagnosticSettings/wt-datafac-DS?api-version=2021-05-01-preview

x-ms-request-id: f667dc88-c6e5-4eb1-ab12-e4685b271b42
x-ms-correlation-request-id: b438f808-33c0-4d7e-b93a-d1d82b4581a2
200 OK

payload

```json
{
"id": "/subscriptions/XXXX/resourcegroups/wt-diagnostic-resources/providers/microsoft.datafactory/factories/wt-acctest/providers/microsoft.insights/diagnosticSettings/wt-datafac-DS",
"type": "Microsoft.Insights/diagnosticSettings",
"name": "wt-datafac-DS",
"location": null,
"kind": null,
"tags": null,
"properties": {
"storageAccountId": null,
"serviceBusRuleId": null,
"workspaceId": "/subscriptions/XXXX/resourceGroups/wt-diagnostic-resources/providers/Microsoft.OperationalInsights/workspaces/wt-testlaw",
"eventHubAuthorizationRuleId": null,
"eventHubName": null,
"metrics": [
{
"category": "AllMetrics",
"enabled": false,
"retentionPolicy": {
"enabled": false,
"days": 0
}
}
],
"logs": [
{
"category": "SSISIntegrationRuntimeLogs",
"categoryGroup": null,
"enabled": true,
"retentionPolicy": {
"enabled": false,
"days": 0
}
},
{
"category": "ActivityRuns",
"categoryGroup": null,
"enabled": false,
"retentionPolicy": {
"enabled": false,
"days": 0
}
},
{
"category": "PipelineRuns",
"categoryGroup": null,
"enabled": false,
"retentionPolicy": {
"enabled": false,
"days": 0
}
},
{
"category": "TriggerRuns",
"categoryGroup": null,
"enabled": false,
"retentionPolicy": {
"enabled": false,
"days": 0
}
},
{
"category": "SandboxPipelineRuns",
"categoryGroup": null,
"enabled": false,
"retentionPolicy": {
"enabled": false,
"days": 0
}
},
{
"category": "SandboxActivityRuns",
"categoryGroup": null,
"enabled": false,
"retentionPolicy": {
"enabled": false,
"days": 0
}
},
{
"category": "SSISPackageEventMessages",
"categoryGroup": null,
"enabled": false,
"retentionPolicy": {
"enabled": false,
"days": 0
}
},
{
"category": "SSISPackageExecutableStatistics",
"categoryGroup": null,
"enabled": false,
"retentionPolicy": {
"enabled": false,
"days": 0
}
},
{
"category": "SSISPackageEventMessageContext",
"categoryGroup": null,
"enabled": false,
"retentionPolicy": {
"enabled": false,
"days": 0
}
},
{
"category": "SSISPackageExecutionComponentPhases",
"categoryGroup": null,
"enabled": false,
"retentionPolicy": {
"enabled": false,
"days": 0
}
},
{
"category": "SSISPackageExecutionDataStatistics",
"categoryGroup": null,
"enabled": false,
"retentionPolicy": {
"enabled": false,
"days": 0
}
}
],
"logAnalyticsDestinationType": "AzureDiagnostics"
},
"identity": null
}
```

Start with the diagnosticSettings API definition linked at specification/monitor/resource-manager/Microsoft.Insights/preview/2021-05-01-preview/diagnosticsSettings_API.json#L323-L327 and the roundtrip_inconsistent_property reference. Reproduce the documented PUT/GET flows for KeyVault and DataFactory, comparing the logAnalyticsDestinationType values. Done means the reported PUT-GET inconsistency is addressed and verified for both target-resource cases.

Written by the indexing model from the issue text.