[FIX] theme_test_custo: remove the console error in test_assets mode

The "Test" key is unnecessary in the tour registry, as it has already been
removed from the Tour Schema (see PR[1]). Also, refactor the tour
definitions to follow the updated step structure.

[1]:https://github.com/odoo/odoo/pull/182887

task-4702436

closes odoo/design-themes#1053

Signed-off-by: Serge Bayet (seba) <seba@odoo.com>

theme_test_custo/static/tests/tours/theme_menu_hierarchies.js

@@ -5,7 +5,6 @@ import { stepUtils } from "@web_tour/tour_service/tour_utils";
 
 wTourUtils.registerWebsitePreviewTour('theme_menu_hierarchies', {
     url: '/example',
-    test: true,
 }, () => [
     stepUtils.waitIframeIsReady(),
     {