Remove RemoteDea test helper

It isn't documented, noone is using it, and
it's painful to keep in sync whenever LocalDea is
changed.

Signed-off-by: Matthew Sykes <matthew.sykes@gmail.com>
instances.json does not forget about instances in stopping state

- Avoids forgetting about containers until they've actually
  been destroyed and cleaned up
- Resumes the stopping/destroying process on startup

[#67263044]

Signed-off-by: Matthew Sykes <matthew.sykes@gmail.com>