purge-container: use lsblk to resolv parent device
purge-container: use lsblk to resolv parent device

Using `lsblk` to resolv the parent device is better than just removing the last
char when passing it to the zap container.

Signed-off-by: Guillaume Abrioux <30a9df5a0293a6108675377fa1673f7aa713f915@redhat.com>
(cherry picked from commit 55298fa80cf542c3d9c0275f085b89fb0e6d61f2)
Signed-off-by: Sébastien Han <62d754cc350e84d3b1c32ae79f976f5348e74a40@redhat.com>

fgal/ceph-ansible,fgal/ceph-ansible