error deleting admin and member groups when deleting COU

The Cou model is not yet using the Changelog Behavior. As such the beforeDelete() method is calling a find() to obtain groups and find the admin and members groups to delete but is finding groups that are either already deleted or are an older version.

The fix for now is that beforeDelete() on the Cou model needs to take into account that some of the groups returned from a find() on the Cou will need to be skipped over when looping to find the associated admin and members groups.