We don't normally want to run VMTests other than on a very limited subset of builders and boards (betty and amd64-generic).


This should be reflected in the way that chromeos_config is organized by making them "opt-in" on a per build config basis, not opt out like they currently are.

One specific example is that "no-vmtest-pre-cq" build configs should be able to go away, since they are no longer a meaningful distinction.