Make option --no-members public in CLI

With many members commands became slow. Making this option public allows
users to speedup searches.

https://fedorahosted.org/freeipa/ticket/4995

Reviewed-By: Martin Babinsky <mbabinsk@redhat.com>

ipalib/plugins/baseldap.py

@@ -1117,7 +1117,7 @@ last, after all sets and adds."""),
                     yield Flag('no_members',
                         doc=_('Suppress processing of membership attributes.'),
                         exclude='webui',
-                        flags=['no_option', 'no_output'],
+                        flags=['no_output'],
                     )
                     break