filter: btrfs-progs subvolume delete output changed

filter: btrfs-progs subvolume delete output changed

btrfs has started emitting new information from
cmd_subvol_delete(), so filter that out or it breaks btrfs/001:

    -Delete subvolume 'SCRATCH_MNT/snap'
    +Delete subvolume (no-commit): 'SCRATCH_MNT/snap'

(Spell "transaction" correctly while we're at it.)

Signed-off-by: Eric Sandeen <sandeen@redhat.com>
Reviewed-by: Eryu Guan <eguan@redhat.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>