Remove memberPrincipal for deleted replicas
    
    When a replica is deleted, its memberPrincipal entries in
    cn=s4u2proxy,cn=etc,SUFFIX were not removed. Then, if the replica
    is reinstalled and connected again, the installer would report
    an error with duplicate value in LDAP.
    
    This patch extends replica cleanup procedure to remove replica
    principal from s4u2proxy configuration.
    
    https://fedorahosted.org/freeipa/ticket/2451