Backport provisionNetworkNow property to june stable version 2025-06-01 (Azure#35399)

* Add provisionNetworkNow property to june stable version 2025-06-01

* Add example for provisionNetworkNow in 2025-06-01.

Author: fmabroukmsft

specification/machinelearningservices/resource-manager/Microsoft.MachineLearningServices/stable/2025-06-01/examples/Workspace/create.json

@@ -41,7 +41,8 @@
               "status": "Approved"
             }
           }
-        ]
+        ],
+        "provisionNetworkNow": false
       }
     }
   },

specification/machinelearningservices/resource-manager/Microsoft.MachineLearningServices/stable/2025-06-01/workspaceRP.json

@@ -1816,6 +1816,10 @@
           "description": "Count of private connections in the workspace",
           "readOnly": true
         },
+        "provisionNetworkNow": {
+          "description": "Set to trigger the provisioning of the managed VNet with the default Options when creating a Workspace with the managed VNet enabled, or else it does nothing.",
+          "type": "boolean"
+        },
         "imageBuildCompute": {
           "description": "The compute name for image build",
           "type": "string"