Adjust modularity_tests to enable the modular repos at the start
    
    As of yesterday's Rawhide, the modular repos are not installed by
    default, so of course all the modular tests fail. So, install
    the repos before running the tests.
    
    This isn't conditionalized on release version as I don't think
    we ever run this test on anything other than Rawhide and
    Branched.
    
    Signed-off-by: Adam Williamson <awilliam@redhat.com>