It's not entirely obvious, but these were not in fact tied to the
old livemedia phase as 087fe9f thought; they are used by modern
phases like imagebuilder and kiwi as well. Restore them, with a
less misleading comment.
Fixes: https://github.com/fedora-iot/iot-distro/issues/131
Signed-off-by: Adam Williamson <awilliam@redhat.com>
