m/c/metroctl: reformat

This appeases my IntelliJ.

Change-Id: I61fa3bea6d5e79eafc25a94880a630fad99c0524
Reviewed-on: https://review.monogon.dev/c/monogon/+/885
Tested-by: Jenkins CI
Reviewed-by: Leopold Schabel <leo@monogon.tech>
Reviewed-by: Mateusz Zalega <mateusz@monogon.tech>
diff --git a/metropolis/cli/metroctl/main.go b/metropolis/cli/metroctl/main.go
index 780b8dd..3729e86 100644
--- a/metropolis/cli/metroctl/main.go
+++ b/metropolis/cli/metroctl/main.go
@@ -51,7 +51,7 @@
 // used.
 func rpcLogger(f string, args ...interface{}) {
 	if flags.verbose {
-		log.Printf("resolver: " + f, args...)
+		log.Printf("resolver: "+f, args...)
 	}
 }