test: remove usage of Polymer helper from menu-bar tests (#9235)

Author: web-padawan

packages/menu-bar/test/sub-menu.test.js

@@ -19,11 +19,8 @@ import {
 import sinon from 'sinon';
 import './menu-bar-test-styles.js';
 import '../src/vaadin-menu-bar.js';
-import { setCancelSyntheticClickEvents } from '@polymer/polymer/lib/utils/settings.js';
 import { isTouch } from '@vaadin/component-base/src/browser-utils.js';
 
-setCancelSyntheticClickEvents(false);
-
 const menuOpenEvent = isTouch ? 'click' : 'mouseover';
 
 describe('sub-menu', () => {