Network icc

guests shouldn't be able communicate between each other when docker param `--icc=false`
Yeah, extra simple an totally predictable.  There's never too much deterministic in unit-test, it's the purpose of them :grinning: 

But see above https://github.com/autotest/autotest-docker/pull/143/files#r13924510 because I think maybe this is not even needed at all.