The new python3-ceph-common deb package (introduced in ceph octopus)
adds a new ceph directory (a parent package in python terms) in
/usr/lib/python3/dist-packages/ceph/. This results in a conflict with
charm-ceph-osd/lib/ceph/. For example, with the current import of
ceph.utils in hooks/ceph_hooks.py, Python finds no utils.py in
/usr/lib/python3/dist-packages/ceph/ and then stops searching.
Therefore, rename lib/ceph to lib/charms_ceph to avoid the conflict.
Depends-On: https://review.opendev.org/#/c/709226
Change-Id: I13ae7c048d8f1eef2ea64b13ae14b51dbfaaf3cd