Add timeout delays for docker test

[kevinwallimann]

Sometimes, docker tests using testcontainers fail with an error message like org.testcontainers.containers.ContainerLaunchException: Timed out waiting for URL to be accessible

This may be fixed by adding a startup delay, e.g.

    container = new KafkaContainer()
    container.withStartupTimeout(Duration.of(5, ChronoUnit.MINUTES))
    container.start();