subtests.docker_cli: Add test run_cidfile

Fixes: https://github.com/autotest/autotest-docker/issues/264

This test is focussed on correct handling of `docker run --cidfile`

Signed-off-by: Lukáš Doktor <ldoktor@redhat.com>
IIRC, ``MustFailDockerCmd`` may be too simplistic for this use.  If there is a failure, it will toss an exception.  If not caught, then this container won't be added to your ``containers`` list, and therefor not get cleaned up.  Maybe use a try...finally... here to guarantee the append happens?