return non-zero exit code on improper flag usage

hack/jenkins/release_update_releases_json.go

@@ -60,7 +60,7 @@ func main() {
 	if *releasesFile == "" || *version == "" {
 		fmt.Println("All flags are required and cannot be empty")
 		flag.PrintDefaults()
-		return
+		os.Exit(1)
 	}
 
 	r, err := getReleases(*releasesFile)

hack/jenkins/test-flake-chart/process_last_90/process_last_90.go

@@ -34,7 +34,7 @@ func main() {
 	if *dataFile == "" || *dataLast90File == "" {
 		fmt.Println("All flags are required and cannot be empty")
 		flag.PrintDefaults()
-		return
+		os.Exit(1)
 	}
 
 	data, err := os.Open(*dataFile)