Issue: Azure Private DNS Resolver Bicep 2nd run fails

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[Template Name goes here](Template link goes here)

### Issue Details

### Repro steps (*if necessary, delete otherwise*)
1. Deploy Azure private DNS resoler Bicep template. Only change, using existing vnet with new subnets
2. First deployment works
3. second deployment will fail about subnet delegation. Looking at the UI, it has the subnet delegation

```
{"status":"Failed","error":{"code":"DeploymentFailed","message":"At least one resource deployment operation failed. Please list deployment operations for details. Please see https://aka.ms/arm-deployment-operations for usage details.","details":[{"code":"Conflict","message":"{\r\n \"status\": \"Failed\",\r\n \"error\": {\r\n \"code\": \"ResourceDeploymentFailure\",\r\n \"message\": \"The 'AzureAsyncOperationWaiting' resource operation completed with terminal provisioning state 'Failed'.\",\r\n
\"details\": [\r\n {\r\n \"code\": \"DeploymentFailed\",\r\n \"message\": \"At least one resource deployment operation failed. Please list deployment operations for details. Please see https://aka.ms/arm-deployment-operations for usage details.\",\r\n \"details\": [\r\n {\r\n \"code\": \"BadRequest\",\r\n \"message\": \"{\\r\\n \\\"error\\\": {\\r\\n \\\"code\\\": \\\"SubnetMissingRequiredDelegation\\\",\\r\\n \\\"message\\\": \\\"Subnet /subscriptions/xxxxxxxx/resourceGroups/rg-network-use2/providers/Microsoft.Network/virtualNetworks/vnet-visualstudioprofessional-use2-10.2.0.0s16/subnets/pvtdnsin-visualstudioprofessional-eus2-10.2.4.0s28 requires any of the following delegation(s) [Microsoft.Network/dnsResolvers] to reference service association link /subscriptions/xxxxxxx/resourceGroups/rg-network-use2/providers/Microsoft.Network/virtualNetworks/vnet-visualstudioprofessional-use2-10.2.0.0s16/subnets/pvtdnsin-visualstudioprofessional-eus2-10.2.4.0s28/serviceAssociationLinks/dnsResolverLink.\\\",\\r\\n \\\"details\\\": []\\r\\n }\\r\\n}\"\r\n }\r\n ]\r\n }\r\n ]\r\n }\r\n}"}]}}
```

Start with the Azure private DNS resolver Bicep template referenced in the issue, deploy it against an existing VNet with new subnets, and inspect the deployment operations after the second run fails. Done means the template can be deployed a second time without the SubnetMissingRequiredDelegation error.

Written by the indexing model from the issue text.