F45 Change: Relocate RPM Repository Configs to /usr

[marmijo]

Fedora 45 relocates all packaged RPM repository configuration from /etc/yum.repos.d to /usr/share/dnf5/repos.d, and GPG keys from /etc/pki/rpm-gpg to /usr/share/pki/rpm-gpg.

• Change Consideration: https://fedoraproject.org/wiki/Changes/RelocateRpmRepoConfigsToUsr
• Tracker bug: https://bugzilla.redhat.com/show_bug.cgi?id=2481848

Relevant Changes:

• Repo configs move from /etc/yum.repos.d → /usr/share/dnf5/repos.d
• GPG keys move from /etc/pki/rpm-gpg → /usr/share/pki/rpm-gpg
• Legacy package managers (DNF4, YUM) will no longer function as system package managers
  • config will largely not exist for them

Why This Affects FCOS

rpm-ostree vendors DNF4, not DNF5. Since distro-provided repo configs will no longer exist in locations DNF4 knows about, client-side package layering will likely stop working.

Additionally, FCOS mounts /usr read-only, so Ignition configs that attempt to write repo files directly to /usr/share/dnf5/repos.d will fail. Users writing repo files to /etc/yum.repos.d via Ignition should be unaffected since that path still works as a DNF5 override, but documentation may need updating.

[travier]

This will also likely impact rpm-ostree composes and thus bootc composes. Thus I think we should bring that up at the bootc level.