Initialize the correct mock chroots
    
    The Hugo uniqueext is meant to exercise `test_mock_uniqueext`:
    
    https://pagure.io/FedoraReview/blob/65ea7b3625b887eb41b3e6b99fcac3faf45e0f8f/f/test/test_misc.py#_452
    
    So it should be run with the default configuration file. Extend
    `init_mockroot` to support this.
    
    Also, since https://pagure.io/FedoraReview/c/cb586353a4ac4034c629c560be158ba16783b9d6
    we have been re-initializing the same configuration twice, the actual
    intention before that is to make sure all current Fedora releases are
    tested.
    
    The default on Fedora 36 is actually Fedora 36 itself, not Rawhide, so
    maybe we should also test Rawhide specifically, since right now '-' and
    'fedora-36-x86_64' are the same, but we can figure that out later.
    
    Signed-off-by: Michel Alexandre Salim <salimma@fedoraproject.org>