jQuery selector should be more flexible

The JS in the selector currently does not work when Drupal appends a random string to the select field (for instance "edit-menu-menu-parent--XwPA9e3r7k8"). This happens when the same form is used multiple times in the page.

I added a patch with a proposed change that modifies the selector so that it matches any ID starting with "edit-menu-menu-parent", allowing it to work correctly even with appended random strings.