Fix link to bots to point to LUCI instead of Buildbot.

Bug: chromium:892712
TBR: [email protected]
Change-Id: I0d1b6085327750ca4c975771d0422089ab6da07b
Reviewed-on: https://chromium-review.googlesource.com/c/1287231


Reviewed-by: Scott Graham <[email protected]>
Commit-Queue: Scott Graham <[email protected]>