rolling_update: add variable to upgrade ceph
rolling_update: add variable to upgrade ceph

My stupid self removed this crucial variable here: 217ce3ca thinking it
was another hard coded variable import where this is actually the
trigger for the upgrade.

Closes: #1071

Signed-off-by: Sébastien Han <62d754cc350e84d3b1c32ae79f976f5348e74a40@redhat.com>

ceph/ceph-ansible,fgal/ceph-ansible,albertomurillo/ceph-ansible,jtaleric/ceph-ansible,guits/ceph-ansible,jtaleric/ceph-ansible,WingkaiHo/ceph-ansible,guits/ceph-ansible,font/ceph-ansible,jsaintrocc/ceph-ansible,travmi/ceph-ansible,fgal/ceph-ansible,travmi/ceph-ansible,albertomurillo/ceph-ansible,jsaintrocc/ceph-ansible,albertomurillo/ceph-ansible,WingkaiHo/ceph-ansible,bengland2/ceph-ansible,font/ceph-ansible,bengland2/ceph-ansible,WingkaiHo/ceph-ansible,ceph/ceph-ansible