7cd3b1b installutils: remove 'install_service_keytab' function

1 file Authored by mbabinsk 2 years ago , Committed by jcholast 2 years ago ,
    installutils: remove 'install_service_keytab' function
    
    This functionality was merged to Service class and is not longer used
    anywhere.
    
    https://fedorahosted.org/freeipa/ticket/6405
    
    Reviewed-By: Stanislav Laznicka <slaznick@redhat.com>