On bots we don't sort due to not being able to store the duration DB. But we should still run the tests marked as slow first.

BUG=v8:5861

Change-Id: Ifa812b3eef15f48e3d3c752c14c3f546b5dd87d1
Reviewed-on: https://chromium-review.googlesource.com/439284Reviewed-by: Jochen Eisinger <jochen@chromium.org>
Reviewed-by: Jakob Kummerow <jkummerow@chromium.org>
Commit-Queue: Michael Achenbach <machenbach@chromium.org>
Cr-Commit-Position: refs/heads/master@{#43057}