Only create DNS SRV records for ready server
    
    When installing multiple replicas in parallel, one replica may create
    SRV entries for other replicas, although the replicas aren't fully
    installed yet. This may cause some services to connect to a server, that
    isn't ready to serve requests.
    
    The DNS IPASystemRecords framework now skips all servers that aren't
    ready IPA masters.
    
    See: https://pagure.io/freeipa/issue/7566
    Signed-off-by: Christian Heimes <cheimes@redhat.com>
    Reviewed-By: Alexander Bokovoy <abokovoy@redhat.com>
    Reviewed-By: Fraser Tweedale <ftweedal@redhat.com>