Py3: fix ipa-replica-conncheck
    
    ipa-replica-conncheck is using the socket methods sendall()
    and sendto() with str. Theses methods expect str params in
    python2 but bytes in python3.
    
    Related to
    https://pagure.io/freeipa/issue/7131
    
    Reviewed-By: Stanislav Laznicka <slaznick@redhat.com>