[FIX] web_tour: ensure Tip template is loaded

The 500 page has `session.is_frontend === undefined` as it has its own
whole HTML template.
In that case, the ajax.loadXML is not done, making the tour crash when
visiting a 500 error page.

This is needed for #29957 that has a test tour on 500 error page.

closes odoo/odoo#30240

addons/web_tour/__manifest__.py

@@ -21,7 +21,7 @@ Odoo Web tours.
         'data/web_tour_demo.xml',
     ],
     'qweb': [
-        "static/src/xml/*.xml",
+        "static/src/xml/debug_manager.xml",
     ],
     'auto_install': True
 }

addons/web_tour/static/src/js/tip.js

@@ -8,6 +8,7 @@ var _t = core._t;
 
 var Tip = Widget.extend({
     template: "Tip",
+    xmlDependencies: ['/web_tour/static/src/xml/tip.xml'],
     events: {
         click: '_onTipClicked',
         mouseenter: "_to_info_mode",

addons/web_tour/static/src/js/tour_service.js

@@ -61,12 +61,8 @@ return session.is_bound.then(function () {
         }, 500);
         var observer = new MutationObserver(check_tooltip);
         var start_service = (function () {
-            var load_def;
 
             return function (observe) {
-                if (load_def === undefined && observe && session.is_frontend) {
-                    load_def = ajax.loadXML('/web_tour/static/src/xml/tip.xml', QWeb);
-                }
 
                 var def = $.Deferred();
                 $(function () {
@@ -74,18 +70,16 @@ return session.is_bound.then(function () {
                      * Once the DOM is ready, we still have to wait all the modules are loaded before completing the tours
                      * registration and starting listening for DOM mutations.
                      */
-                    $.when(load_def).then(function () {
-                        _.defer(function () {
-                            tour_manager._register_all(observe);
-                            if (observe) {
-                                observer.observe(document.body, {
-                                    attributes: true,
-                                    childList: true,
-                                    subtree: true,
-                                });
-                            }
-                            def.resolve();
-                        });
+                    _.defer(function () {
+                        tour_manager._register_all(observe);
+                        if (observe) {
+                            observer.observe(document.body, {
+                                attributes: true,
+                                childList: true,
+                                subtree: true,
+                            });
+                        }
+                        def.resolve();
                     });
                 });
                 return def;