add upgrade/firefly-x based on dumpling-x

It is a s/dumpling/firefly/ mostly. With the exception of
rados/test-upgrade-firefly.sh which is dumpling specific.

The 'mon warn on legacy crush tunables: false' are dropped because they
no longer apply to firefly.

Signed-off-by: Loic Dachary <loic@dachary.org>