Temporarily mark aarch64 Cloud-Base to be failable in order to get some composes out.
    
    aarch64 cloud is blocking, but it's hitting:
    https://bugzilla.redhat.com/show_bug.cgi?id=1722181
    and failing the composes. Due to other issues we haven't had composes
    for a while before that either, so it's getting to be a long time.
    Hopefully some workaround will at least appear in a few days.
    If not, we can revert this and start failing again for a while.
    
    Signed-off-by: Kevin Fenzi <kevin@scrye.com>