monitoring: add more panels to Grafana repo-updater dashboard
Created by: unknwon
Raw notes:
- Is syncing health?
- Data points for syncing completes, how much time and how many repos for each sync
- Schedule queue, how big is it
- What do we need if customer thinks repos are not updating
- Are repos being refreshed appropriately on gitservers?
- Number of update requests to gitservers
- Bonus: How is indexing doing on Zoekt?