[FIX] theme_avantgarde: add missing snippet in tour

This was probably removed at some point because the snippet was empty
but it is not anymore in 14.3 so we need it for shape connection.

Part of https://github.com/odoo/design-themes/pull/2
task-2491890

theme_avantgarde/static/src/js/tour.js

@@ -17,6 +17,10 @@ const snippets = [
         id: 's_text_image',
         name: 'Image - Text',
     },
+    {
+        id: 's_images_wall',
+        name: 'Images Wall',
+    },
     {
         id: 's_references',
         name: 'References',