Tests are temporarily limited to a small subset of boards. We're still
fixing Ozone GPU initialization on mustash. In the mean time it's
important that we don't regress other parts of mustash login. By
limiting to a few boards we can get mustash tests on the Chrome PFQ ToT
informational waterfall, which will catch regressions due to GPU code
changes in Chrome ToT.

http://crbug.com/708002