tripleo_podman_purge: try to use -f when pruning images

Recent version of podman requires yes/no when pruning images, except if
-f is given as an argument.

Let's first try the new way, and fallback on the old method.

Change-Id: Ie2a70d4ec40c2a2142b0857822edd5122b63c941
Closes-Bug: #1889418

tripleo_ansible/roles/tripleo_podman/tasks/tripleo_podman_purge.yml

@@ -15,11 +15,17 @@
 # under the License.
 
 
-- name: Podman prune
+- name: Podman image prune
   become: true
   block:
+    - name: Clean podman images
+      command: podman image prune -a -f
+  rescue:
+    # In case -f isn't available yet, we fallback to old way.
+    # https://bugs.launchpad.net/tripleo/+bug/1889418
     - name: Clean podman images
       command: podman image prune -a
 
-    - name: Clean podman volumes
-      command: podman volume prune -f
+- name: Clean podman volumes
+  become: true
+  command: podman volume prune -f