WIP: Refresh Podman user namespace mappings on Rawhide

Some CI jobs on Fedora Rawhide failed with rootless Podman builds due to
stale or missing UID/GID mappings, even after installing
shadow-utils-subid-devel:

    Error: cannot find mappings for user zuul-worker in /etc/subuid

Force a refresh of Podman’s user namespace mappings with
`podman system migrate`, which re-reads /etc/subuid and /etc/subgid
and applies default ranges when available.

Once the Rawhide base image includes proper mappings by default,
this workaround can be removed.

https://github.com/containers/toolbox/pull/1689

playbooks/dependencies-fedora.yaml

@@ -39,6 +39,11 @@
       - udisks2
     use: "{{ 'dnf' if zuul.attempts > 1 else 'auto' }}"
 
+- name: Force Podman to refresh user namespace mappings
+  become: true
+  command: podman system migrate
+  ignore_errors: true
+
 - name: Ensure that 'p11-kit server' is absent
   become: yes
   package: