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.
Currently the docker based test setup requires the docker cli and
docker-compose. However on systems that only use podman this doesn't
work. While there is a docker cli wrapper for podman docker-compose
doesn't work together with podman. However there is also
podman-compose which supports the same docker-compose yaml files.
Thus adapt the script such that it finds either the docker or podman
executables and uses them.
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.