Allow to specify what container runtime to use instead of preferring docker when installing database

[doberkofler]

When having installed docker and podman it is not possible to use podman as the container runtime.
The buildContainerImage.sh (and most likely all others) simply prefer Docker over Podman and therefore malke it impossible to use Podman.
It would be helpful to habe an option or environment flag that specifies what engine to use or to overwrite the default detection.

# Check container runtime
checkContainerRuntime() {
  CONTAINER_RUNTIME=$(which docker 2>/dev/null) ||
    CONTAINER_RUNTIME=$(which podman 2>/dev/null) ||
    {
      echo "No docker or podman executable found in your PATH"
      exit 1
    }

  if "${CONTAINER_RUNTIME}" info | grep -i -q buildahversion; then
    checkPodmanVersion
  else
    checkDockerVersion
  fi
}