[Train-only] Configure podman registries during a minor update.

If a new insecure registry would be added in the update prepare
this wouldn't be included in the Podman's unsecure registries
configuration. Leading to a failed update as the overcloud nodes
wouldn't be able to reach the insecure registry.

Reusing the upgrade_taks that took care of configuring the
insecure registries, as well as adding (if it wasn't already) the
underclouds hostname in /etc/hosts. In theory, these tasks should
be idempotent. So, if all these configurations are already done the
tasks should not do anything.

Change-Id: I8a73fd31ac365146439191111bacfb4b6c5b9ba3

deployment/podman/podman-baremetal-ansible.yaml

@@ -160,7 +160,7 @@ outputs:
         - name: Run podman install
           when:
             - step|int == 1
-          block:
+          block: &podman_configure_registry
             # This is needed when moving from Docker to Podman. The SELinux context
             # is wrong for podman, especially if the directory was created by
             # docker itself.
@@ -223,6 +223,11 @@ outputs:
                 - never
                 - system_upgrade
                 - system_upgrade_prepare
+      update_tasks:
+        - name: Run podman registry configuration
+          when:
+            - step|int == 1
+          block: *podman_configure_registry
 
       post_upgrade_tasks:
         - name: Purge everything about docker on the host