This mirrors the configuration in Nodepool for using TLS-enabled
ZooKeeper in tests. We use the ensure-zookeeper role in order
to get a newer ZooKeeper than is supplied in bionic.
We currently have the test-setup.sh script that installs and
configures the services that are needed to run the zuul test
suite. However this needs mysql, postgres and zookeeper installed into
the system. It also messes with tmpfs mounts of zookeeper. This adds a
docker-compose based test setup that can ease the setup of the test
requirements on a developer machine.