Give linux-fieldtrial-rel FYI builder a mastername

I look forward to the day that this is no longer necessary, but
for now masternames are still keys into the chromium_tests bot_config
dictionary.

TBR: jbudorick
Bug: 971387
Change-Id: I2d79fb35260c615900b8ae0cd7d4b7a9cacc9711
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1658632
Reviewed-by: Aaron Gable <agable@chromium.org>
Commit-Queue: Aaron Gable <agable@chromium.org>
Auto-Submit: Aaron Gable <agable@chromium.org>
Cr-Commit-Position: refs/heads/master@{#669054}
1 file changed