rolling_update: fix dest path for mgr keys fetching
rolling_update: fix dest path for mgr keys fetching

the role `ceph-mgr` that is played later in the playbook fails because
the destination path for the fetched keys is wrong.
This patch fix the destination path used in the task `fetch ceph mgr
key(s)` so there is no mismatch.

Closes: https://bugzilla.redhat.com/show_bug.cgi?id=1574995

Signed-off-by: Guillaume Abrioux <30a9df5a0293a6108675377fa1673f7aa713f915@redhat.com>

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