fix(appengine): Update appengine/hello-world/flexible_nodejs16_and_earlier/app.js

Co-authored-by: code-review-assist-experimental[bot] <172519755+code-review-assist-experimental[bot]@users.noreply.github.com>

Author: iennae

appengine/hello-world/flexible_nodejs16_and_earlier/app.js

@@ -14,7 +14,7 @@
 
 'use strict';
 
-// [START gae_flex_quickstart_v1] # rgeion tag test
+// [START gae_flex_quickstart_v1]
 const express = require('express');
 
 const app = express();