[FIX] web_editor: restore invisible snippet activation

The loading effect of the left panel was conflicting with the invisible
snippet activation. This is to be reviewed with the new UI anyway, so
the loading effect is just removed in that case for now.

closes odoo/odoo#52676

Signed-off-by: Quentin Smetz (qsm) <qsm@odoo.com>

addons/web_editor/static/src/js/editor/snippets.editor.js

@@ -2057,8 +2057,6 @@ var SnippetsMenu = Widget.extend({
      * @param {Event} ev
      */
     _onInvisibleEntryClick: async function (ev) {
-        this._addTabLoading();
-
         ev.preventDefault();
         const $snippet = $(this.invisibleDOMMap.get(ev.currentTarget));
         const isVisible = await this._mutex.exec(async () => {