With several buckets, it appears the gerrit tryjobs plugin only
displays the first bucket. In that case we want to display the main
UCI bucket rather than the win stragglers in buildbot.

No-try: True
Tbr: fbarchard@chromium.org
Bug: chromium:869249
Change-Id: I50dcbf668d29becbe493601be8b9db089de78b85
Reviewed-on: https://chromium-review.googlesource.com/1170688Reviewed-by: Patrik Höglund <phoglund@chromium.org>
Commit-Queue: Patrik Höglund <phoglund@chromium.org>