Add CI test to verify db/schema.rb matches the latest migration version in db/migrate
We have often seen someone check in a migration only to forget to update the date or did not resolve a conflict properly in db/schema.rb. It just happened yesterday in #21894 (closed). I think we should add a simple CI test that does:
- Scan the db/migrate directory and find the latest timestamp
- Make sure that the timestamp in db/migrate matches