Also, move the --timeout=900 flag from the recipe to the mb.py script. That way it is passed as an arg to gtest-parallel and not to the test executable.
BUG=webrtc:7568
NOTRY=True
Review-Url: https://codereview.webrtc.org/2862803002
Cr-Commit-Position: refs/heads/master@{#18015}