test: restore no-op function in test

Remove common.mustCall() in test that might connect to a server already
running on the local host.

PR-URL: #14065
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Refael Ackermann <refack@gmail.com>
Reviewed-By: Yuta Hiroto <hello@about-hiroppy.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>

test/parallel/test-http-hostname-typechecking.js

@@ -1,5 +1,5 @@
 'use strict';
-const common = require('../common');
+require('../common');
 
 const assert = require('assert');
 const http = require('http');
@@ -21,7 +21,7 @@ vals.forEach((v) => {
 // These values are OK and should not throw synchronously
 ['', undefined, null].forEach((v) => {
   assert.doesNotThrow(() => {
-    http.request({hostname: v}).on('error', common.mustCall()).end();
-    http.request({host: v}).on('error', common.mustCall()).end();
+    http.request({hostname: v}).on('error', () => {}).end();
+    http.request({host: v}).on('error', () => {}).end();
   });
 });