crash when removing a replica
when a server is removed from the topology the plugin tries to remove the
credentials from the replica and the bind dn group.
It performs an internal search for the ldap principal, but can fail if it was already removed
Due to an unitialized variable in this case it can eitehr crash or erroneously remove all
Reviewed-By: Fraser Tweedale <email@example.com>
Reviewed-By: Petr Vobornik <firstname.lastname@example.org>