[FIX] web_tour: load xml at test start

Before this commit, the template of the "Tip" widget was loaded on test runtime
and caused a concurrency issue.

Now, the template is loaded before the test suite is launched and is ready when
the test is executed.

closes odoo/odoo#48589

Signed-off-by: Aaron Bohy (aab) <aab@odoo.com>

addons/web_tour/static/tests/tour_manager_tests.js

@@ -1,9 +1,15 @@
-odoo.define('web_tour.tour_manager_tests', function (require) {
+odoo.define('web_tour.tour_manager_tests', async function (require) {
     "use strict";
 
     const TourManager = require('web_tour.TourManager');
     const testUtils = require('web.test_utils');
 
+    const ajax = require('web.ajax');
+    const { qweb } = require('web.core');
+
+    // Pre-load the Tip widget template
+    await ajax.loadXML('/web_tour/static/src/xml/tip.xml', qweb);
+
     /**
      * Create a widget and a TourManager instance with a list of given Tour objects.
      * @see TourManager.register() for more details on the Tours registry system.