[REF] website: remove useless code

Part of https://github.com/odoo/odoo/commit/f4ba72a7593b67595852fc52ec0997d3276dbc67
became useless after forward-port in the new editor. Indeed, that
commit handled what happened with data-editor-message attributes on
save but as the new editor can discard changes without reloading the
page, the forward-port of that commit made the code handle the attribute
removal on editor *close*.

closes odoo/odoo#31143

addons/website/static/src/js/menu/edit.js

@@ -123,19 +123,10 @@ var EditPageMenu = websiteNavbarData.WebsiteNavbarActionWidget.extend({
      * expects that the save action is performed. So, this empty action is
      * defined here so that all users have an 'on_save' related action.
      *
-     * As explained above, that action should always be defined in the current
-     * implementation (even an empty one) but in fact it is also needed to
-     * remove the data-editor-message attributes which are added when entering
-     * edition.
-     *
      * @private
      * @todo improve the system to somehow declare required/optional actions
      */
-    _onSave: function () {
-        if (this.$editorMessageElements) {
-            this.$editorMessageElements.removeAttr('data-editor-message');
-        }
-    },
+    _onSave: function () {},
 
     //--------------------------------------------------------------------------
     // Private