Not replacing ubuntu1604 docker node for now. Once these have been
heavily tested and vetted, it will be much safer to move the other
docker node to Ubuntu 18.04 & v2 hardware.
Issue: RELENG-2071
Change-Id: Id3d5d06256371948f52e2454de39d87304908bb2 Signed-off-by: Eric Ball <eball@linuxfoundation.org>