Run correct subset of docker compose containers when withServices/withScaledService used

[rnorth]

Replaces #2250, fixes #2191

My comment on #2250:

The current implementation fails to limit the running services. My misunderstanding was thinking that it was failing to launch any containers which are in withServices but not in withScaledServices.

Actually that is and always has been fine, but we're getting services launched that we do no want.

e.g. with a docker-compose.yml file like:

redis:
  image: redis
db:
  image: orchardup/mysql
  environment:
    MYSQL_DATABASE: wordpress

and

    public DockerComposeContainer environment = new DockerComposeContainer(new File("src/test/resources/compose-test.yml"))
        .withServices("redis");

(taken from the test)

... we'd expect on redis to come up, but actually db is launched too.

The same goes for:

    public DockerComposeContainer environment = new DockerComposeContainer(new File("src/test/resources/compose-test.yml"))
        .withServices("redis") // with or without this line
        .withScaledService("redis", 2);

... we get 2 redis, plus one db that wasn't asked for.

We should absolutely fix this.