mgr/volumes: Disable quota for mgr libcephfs connection

mgr/volumes: Disable quota for mgr libcephfs connection

This is done to give 'mgr' libcephfs connection right to bypass
quota. The mgr/volumes plugin maintains configuration files
with in the directory where the user has enforced quota. So
when the quota is met, certain mgr/volumes apis don't work as
intended. e.g., When subvolumegroup quota is met, the group's
subvolume removal with '--retain-snapshots' fails.

Fixes: https://tracker.ceph.com/issues/53509
Signed-off-by: Kotresh HR <khiremat@redhat.com>