sqlvm-alwayson-cluster fails with extension provisioning timeout

101-sql-vm-ag-setup (azure-quickstart-templates/101-sql-vm-ag-setup/)

### Issue Details

{"code":"DeploymentFailed","message":"At least one resource deployment operation failed. Please list deployment operations for details. Please see https://aka.ms/DeployOperations for usage details.","details":[{"code":"Conflict","message":"{\r\n \"status\": \"Failed\",\r\n \"error\": {\r\n \"code\": \"ResourceDeploymentFailure\",\r\n \"message\": \"The resource operation completed with terminal provisioning state 'Failed'.\",\r\n \"details\": [\r\n {\r\n \"code\": \"VMExtensionProvisioningTimeout\",\r\n \"message\": \"Provisioning of VM extension CreateFileShareWitness has timed out. Extension provisioning has taken too long to complete. The extension did not report a message. More information on troubleshooting is available at https://aka.ms/VMExtensionDSCWindowsTroubleshoot\"\r\n }\r\n ]\r\n }\r\n}"}]}

{"code":"DeploymentFailed","message":"At least one resource deployment operation failed. Please list deployment operations for details. Please see https://aka.ms/DeployOperations for usage details.","details":[{"code":"Conflict","message":"{\r\n \"status\": \"Failed\",\r\n \"error\": {\r\n \"code\": \"ResourceDeploymentFailure\",\r\n \"message\": \"The resource operation completed with terminal provisioning state 'Failed'.\",\r\n \"details\": [\r\n {\r\n \"code\": \"VMExtensionProvisioningTimeout\",\r\n \"message\": \"Provisioning of VM extension CreateBDC has timed out. Extension provisioning has taken too long to complete. The extension did not report a message. More information on troubleshooting is available at https://aka.ms/VMExtensionDSCWindowsTroubleshoot\"\r\n }\r\n ]\r\n }\r\n}"}]}

Start in 101-sql-vm-ag-setup and investigate the CreateFileShareWitness and CreateBDC VM extension provisioning operations. Use the reported deployment failures and Azure deployment-operation troubleshooting link to identify why provisioning times out; done means the SQL Always On cluster deployment completes without either extension timing out.

Written by the indexing model from the issue text.