dashboard: retry setting rgw-credentials

for some reason, this task can fail in the CI.
Adding a retry can help to avoid this failure.

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

roles/ceph-dashboard/tasks/configure_dashboard.yml

@@ -258,6 +258,9 @@
     - name: set the rgw credentials
       command: "{{ container_exec_cmd }} ceph --cluster {{ cluster }} dashboard set-rgw-credentials"
       changed_when: false
+      register: result
+      until: result is succeeded
+      retries: 5
 
     - name: set the rgw admin resource
       command: "{{ container_exec_cmd }} ceph --cluster {{ cluster }} dashboard set-rgw-api-admin-resource {{ dashboard_rgw_api_admin_resource }}"