Move Geo event log gap tracking to database

Now the Geo log events are tracking in redis. It would make more sense to use the tracking database for this, and probably the geo_event_log_state table.

To be done

• Report min event log id separately from the min gap id
• Report gap count and min id in Prometheus
• Make sure events aren't pruned up to min_gap_id - 1 (at the moment also min_gap_id might be pruned)