Extend the generate-update-metadata logic to not query the RPM db but instead pick the versions from the new paths where the grub2 & shim binaries will be installed in /usr/lib/(shim|grub)/%{version}-%{release}/EFI/... when we land https://fedoraproject.org/wiki/Changes/BootLoaderUpdatesPhase1.

See:

• https://fedoraproject.org/wiki/Changes/BootLoaderUpdatesPhase1
• https://gitlab.com/fedora/bootc/tracker/-/issues/61
• https://gitlab.com/fedora/bootc/base-images/-/merge_requests/90

Draft PRs for GRUB & shim that will use the new paths:

• https://src.fedoraproject.org/rpms/grub2/pull-request/136
• https://src.fedoraproject.org/rpms/grub2/pull-request/140
• https://src.fedoraproject.org/rpms/shim/pull-request/4