As you have probably noticed, docker stop as well as docker rm exit with a status code indicating failure if the container is not existent or not running. This results in your build failing.
If you can cope with the error messages in your build log you can do this little trick to prevent the shell command of failing:
docker stop rabbitmq || true && docker rm rabbitmq || true
In the case that one of the docker command fails, true is called which always exits with a status code indicating success.