test: set UPDATE_CEPH_DOCKER_IMAGE_TAG for jewel tests
test: set UPDATE_CEPH_DOCKER_IMAGE_TAG for jewel tests

We want to be explict here and update to luminous and not
the 'latest' tag.

Signed-off-by: Andrew Schoen <1bb641dc23c3a93cce4eee683bcf4b2bea7903a3@redhat.com>
(cherry picked from commit a8509fbc9c0328670224f608abea17d8e64257ab)
Signed-off-by: Sébastien Han <62d754cc350e84d3b1c32ae79f976f5348e74a40@redhat.com>

fgal/ceph-ansible,fgal/ceph-ansible