update: only run post osd upgrade play on 1 mon

There is no need to run these tasks n times from each monitor.

Signed-off-by: Guillaume Abrioux <gabrioux@redhat.com>
(cherry picked from commit c878e99589)

infrastructure-playbooks/rolling_update.yml

@@ -456,12 +456,10 @@
     - name: get osd versions
       command: "{{ docker_exec_cmd_update_osd|default('') }} ceph --cluster {{ cluster }} versions"
       register: ceph_versions
-      delegate_to: "{{ groups[mon_group_name][0] }}"
 
     - name: set_fact ceph_versions_osd
       set_fact:
         ceph_versions_osd: "{{ (ceph_versions.stdout|from_json).osd }}"
-      delegate_to: "{{ groups[mon_group_name][0] }}"
 
     # length == 1 means there is a single osds versions entry
     # thus all the osds are running the same version