This PS updates the mon-check reap-zombies python script to consider
the more recent Ceph changes, including the fact that there is now
a v1 and v2 backend. In addition, it executes the reap-zombies script
with the python3 binary, as the basic 'python' binary does not exist
in the container.
Change-Id: Id079671f03cc5ddbe694f2aa8c9d2480dc573983
f26d4db145