Fix uniqueness plugins
    
    * add uniqueness-subtree-entries-oc:posixAccount to ensure idviews users
    will not be forced to have unique uid
    
    * remove unneded update plugins -> update was moved to .update file
    
    * add uniqueness-across-all-subtrees required by user lifecycle
    management
    
    Reviewed-By: Alexander Bokovoy <abokovoy@redhat.com>