frontend: Refetch resource document after updating

Noticed while testing Tags field patching that the PATCH response
did not contain the updated Tags. I had to GET the resource again
to see the correct set of Tags.

frontend/pkg/frontend/frontend.go

@@ -565,6 +565,13 @@ func (f *Frontend) ArmResourceCreateOrUpdate(writer http.ResponseWriter, request
 		if updated {
 			logger.Info(fmt.Sprintf("document updated for %s", resourceID))
 		}
+		// Get the updated resource document for the response.
+		doc, err = f.dbClient.GetResourceDoc(ctx, resourceID)
+		if err != nil {
+			logger.Error(err.Error())
+			arm.WriteInternalServerError(writer)
+			return
+		}
 	}
 
 	responseBody, err := marshalCSCluster(csCluster, doc, versionedInterface)

frontend/pkg/frontend/node_pool.go

@@ -250,6 +250,13 @@ func (f *Frontend) CreateOrUpdateNodePool(writer http.ResponseWriter, request *h
 		if updated {
 			logger.Info(fmt.Sprintf("document updated for %s", resourceID))
 		}
+		// Get the updated resource document for the response.
+		doc, err = f.dbClient.GetResourceDoc(ctx, resourceID)
+		if err != nil {
+			logger.Error(err.Error())
+			arm.WriteInternalServerError(writer)
+			return
+		}
 	}
 
 	responseBody, err := marshalCSNodePool(csNodePool, doc, versionedInterface)