Devicelab microbenchmarks take a long time, are close to the timeout limit

This PR failed due to timeout limit: https://github.com/flutter/flutter/pull/143799

I don't know if this test is too big, if the suite has too much tests and should be split, or what? Could anyone that is more familiar with that please take a look for me? I wish we found a way to land this test, even if we have to make it smaller.