This should prevent the issues we've seen recently where cms modules are
imported by the running lms process, resulting in two celery instances
being created and tasks intermittently being registered to the wrong
instance (and therefore effectively lost.)
In commit ab6bf348d4/PR #25822 we tried to ensure that only one or the
other of the instances was created by adding a startup check.
Unfortunately, there's an external shared library that refers directly
to the lms celery, causing a startup failure in cms, so we had to revert
it. Rather than waiting to fix that library, this commit collapses
the two instances together so that there is only ever one.
0c57a02119