Use a temporary timeout multipler for trace tests. The trace tests upload is frequently timing out on our test infra because of the size of the test suite. Until we can find a better solution we can increase the timeout non-invasively using an environment variable. Bug: angleproject:6854 Change-Id: Ifbe43c4d9dc8928cf35df8a26b844f884c90eb9d Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/3427560 Reviewed-by: Cody Northrop <cnorthrop@google.com> Reviewed-by: Yuly Novikov <ynovikov@chromium.org> Commit-Queue: Jamie Madill <jmadill@chromium.org>