rolling_update: register container osd units
rolling_update: register container osd units

Before running the upgrade, let's call systemd to collect unit names
instead of relaying on the device list. This is more accurate and fix
the osd_auto_discovery scenario too.

Closes: https://bugzilla.redhat.com/show_bug.cgi?id=1613626
Signed-off-by: Sébastien Han <62d754cc350e84d3b1c32ae79f976f5348e74a40@redhat.com>

fgal/ceph-ansible,ceph/ceph-ansible,fgal/ceph-ansible,ceph/ceph-ansible