filters/configuration[cib2pcscmd]: avoid "pcs cluster cib <file> --config"
    
    This is to solve original misunderstanding wrt. symmetry in "--config"
    between "cib" and "cib-push" pcs subcommands being desired, while in
    fact the former is hardly useful for anything as pcs cannot use such
    output (even if equivalent to full-blown CIB, configuration wise) for
    in-file (via "-f <file>") modifications at this time.
    
    Hence, drop --config in "cib" (dump configuration to file) case, but
    continue using that for "cib-push" (propagate configuration to live
    Pacemaker cluster) happily as this doesn't bear any conflict and
    is downright desired.
    
    Resolves: <https://bugzilla.redhat.com/1328078>.
    
    Signed-off-by: Jan Pokorný <jpokorny@redhat.com>