Merge pull request #44854 from kotreshhr/subvolumegroup_ls

mgr/volumes: Fix subvolumegroup ls

Reviewed-by: Venky Shankar <vshankar@redhat.com>

diff --cc qa/tasks/cephfs/test_volumes.py
Simple merge

diff --cc src/pybind/mgr/volumes/fs/fs_util.py
Simple merge

diff --cc src/pybind/mgr/volumes/fs/volume.py
Simple merge