Geo - Geo::JobArtifactRegistryFinder#find_registry_differences should ignore expired ones

While working on !34590 (merged), I notice that we forgot ignoring the expired job artifacts while making the registry table the SSOT for job artifacts in !25378 (merged).

We should change the Geo::JobArtifactRegistryFinder#find_registry_differences method to ignore them. We don't need to perform a clean up since the Geo::RegistryConsistencyWorker will remove them.