Add metrics for:
 - Geo event log count
 - Geo event log max ID
 - Repository created max ID
 - Repository updated max ID
 - Repository deleted max ID
 - Repository renamed max ID
 - Repositories changed max ID
 - LFS object deleted max ID
 - Job artifact deleted max ID
 - Hashed storage migrated max ID
 - Hashed storage attachments max ID

It logs maximum IDs because Geo::PruneEventLogWorker might remove old
events, so COUNT isn't representing an accurate accumulate value for
the number of events created.

Closes gitlab-org/gitlab-ee#4688.