`t.sh` and `tn.sh` now each use a distinct GOCACHE. This causes
back-to-back invocations of the unittests in config and config-next
to not incorrectly skip tests whose behavior changes between
those two environments.
- Remove environment variables no longer referenced in CI
- Standardize `environment` mapping to use key + value
- Standardize on two space indent
- Alias `image` to make version updates easier
Fixes#5334
Docker container should load the appropriate schema (`sa/_db` or
`sa/_db-next`) for the given configuration.
- Add `docker-compose.next.yml` docker-compose overrides
- Detect when to apply `sa/_db-next/migrations`
- Detect mismatch between `goose dbversion` and the latest migration
- Symlink `promoted` schema back to `sa/_db-next/migrations`
- Add tooling to consistently promote/demote schema migrations
Fixes#5300