Update awful 'stable' hack to F32
    
    Well, I've done this for two releases now, so I guess it's a
    tradition! :(
    
    Same problem as before: after fedora-release gets bumped to -1
    or higher, the live image that we build in the updates tests no
    longer has the pre-release note, but we are still expecting it
    in the install test because the release is not "stable" yet so
    far as our source of truth (now Bodhi, not collections) knows.
    Even with a whole cycle to think about it, I haven't come up
    with a better way to fix this, unfortunately.
    
    Signed-off-by: Adam Williamson <awilliam@redhat.com>