rolling_update: do not fail the playbook if nfs-ganesha is not present

The rolling update playbook was attempting to stop the
nfs-ganesha service on nodes where jewel is still installed.
The nfs-ganesha service did not exist in jewel so the task fails.

Signed-off-by: Andrew Schoen <aschoen@redhat.com>

infrastructure-playbooks/rolling_update.yml

@@ -535,11 +535,15 @@
   become: True
 
   pre_tasks:
+    # failed_when: false is here so that if we upgrade
+    # from a version of ceph that does not have nfs-ganesha
+    # then this task will not fail
     - name: stop ceph nfs
       systemd:
         name: nfs-ganesha
         state: stopped
         enabled: yes
+      failed_when: false
       when:
         - not containerized_deployment