Assume Docker Compose v2 if `docker-compose` is missing in integration test

[supahgreg]

If docker-compose is not available during integration testing, assume Docker Compose v2 (docker compose by default) is to be used.

https://www.docker.com/blog/announcing-compose-v2-general-availability/

Notes for Reviewers

• [ ] The commit history must be preserved - please use the rebase-merge or standard merge option instead of squash-merge
• [ ] Sync up with the author before merging