Remove Chromium Mac 10.13 FYI bot

We have Mac 10.13 coverage on the main waterfall now.

Bug: 973189
Change-Id: I832b27c94d19912f7de0b3159a23a752b2047f38
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1653836
Commit-Queue: Aaron Gable <agable@chromium.org>
Reviewed-by: Dirk Pranke <dpranke@chromium.org>
Auto-Submit: Aaron Gable <agable@chromium.org>
Cr-Original-Commit-Position: refs/heads/master@{#668675}
Cr-Mirrored-From: https://chromium.googlesource.com/chromium/src
Cr-Mirrored-Commit: aec8fb8fad8d8ff55111d465a01c3acab54e2fe7
4 files changed