RFC 697: Ensure oobmigration checks are respected in the migrator

Created by: efritz

See RFC 697: Multiple version upgrades.

We need to ensure that the migrator will fail-fast (and not update the database schema) while the out-of-band migration status check would fail. This slightly overlaps with #38047 (closed), but can provide additional value until we complete the multiple version upgrade effort.

We can get into a situation where the schema is updated, but the frontend refuses to start because an out-of-band migration has not completed. Downgrades can be difficult in this situation, or at least confusing from an admin perspective.

We should copy the condition that checks the minor version distance into the migrator so that the error message comes from the migrator and not only from the frontend. When this condition is detected we should do nothing to the state of the instance's data.