lorax: drop unnecessary options
    
    there's no need to pass --noupgrade or --squashfs-only any more.
    --noupgrade has done nothing since we gave up on fedup in 2015
    (lorax still accepts it for backwards compatibility, but ignores
    it). --squashfs-only is effectively the default since 41.2 -
    see https://github.com/weldr/lorax/commit/01dd27a .
    
    Signed-off-by: Adam Williamson <awilliam@redhat.com>