Switch to docker compose subcommand

[perlpunk]

The docker-compose tool isn't maintained anymore and should be replaced by the docker compose subcommand:
https://docs.docker.com/compose/migrate/

docker-compose: command not found

[Martchus]

The test failed with:

-- Blocking request (http://nginx:9526/api/v1/jobs)
-- Connect cb13661a1d583e5cc003debb95f4aaf9 (http://nginx:9526)
Connection refused
Error executing a job
webui-1  | Waiting for DB creation

I retried the test run but maybe it is related to this change.

[perlpunk]

I'm debugging this

[perlpunk]

export COMPOSE_COMPATIBILITY=1 at the top of tools/test_containers_compose did not help

[perlpunk]

Adding --compatibility worked. We can use this as a temporary workaround to get tests passing.

[perlpunk]

https://docs.docker.com/compose/migrate/#service-container-names suggests that the changed container names (- instead of _) are the problem. I currently don't see a place where we use the container names explicitly though.