purge: add monitoring group in final cleanup play

This adds the monitoring group in the "final cleanup play" so any cid
files generated are well removed when purging the cluster.

Closes: https://bugzilla.redhat.com/show_bug.cgi?id=1974536

Signed-off-by: Guillaume Abrioux <gabrioux@redhat.com>
(cherry picked from commit 037d8cd)

infrastructure-playbooks/purge-container-cluster.yml

@@ -557,6 +557,7 @@
     - "{{ rbdmirror_group_name|default('rbdmirrors') }}"
     - "{{ nfs_group_name|default('nfss') }}"
     - "{{ mgr_group_name|default('mgrs') }}"
+    - "{{ grafana_server_group_name|default('grafana-server') }}"
 
   become: true