treewide: replace deprecated grpc.Dial with grpc.NewClient

Change-Id: I925912ca1ee01d547fd9c1813eb083a2cd9a590a
Reviewed-on: https://review.monogon.dev/c/monogon/+/3858
Reviewed-by: Jan Schär <jan@monogon.tech>
Tested-by: Jenkins CI
diff --git a/metropolis/cli/metroctl/cmd_cluster_takeownership.go b/metropolis/cli/metroctl/cmd_cluster_takeownership.go
index 3566ea0..d917bc3 100644
--- a/metropolis/cli/metroctl/cmd_cluster_takeownership.go
+++ b/metropolis/cli/metroctl/cmd_cluster_takeownership.go
@@ -64,9 +64,9 @@
 		}
 		opts = append(opts, grpc.WithTransportCredentials(creds))
 
-		cc, err := grpc.Dial(resolver.MetropolisControlAddress, opts...)
+		cc, err := grpc.NewClient(resolver.MetropolisControlAddress, opts...)
 		if err != nil {
-			return fmt.Errorf("while dialing the cluster: %w", err)
+			return fmt.Errorf("while creating client: %w", err)
 		}
 		aaa := apb.NewAAAClient(cc)