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.
Change-Id: I2d1c5e1713c51de376653b35266819fd380e8891
2facdf1033