Add alert for G3 Canary
Add alert for G3 Canary

Bug: skia:12521
Change-Id: I3870b87e02fca016373bfd9bacf43252ace2902e
Reviewed-on: https://skia-review.googlesource.com/c/buildbot/+/487456
Reviewed-by: Joe Gregorio <b9cf2471ff6d33504cafe8e6f356b732b2cadced@google.com>
Commit-Queue: Ravi Mistry <9fa2e7438b8cb730f96b74865492597170561628@google.com>

google/skia-buildbot,google/skia-buildbot,google/skia-buildbot,google/skia-buildbot,google/skia-buildbot,google/skia-buildbot,google/skia-buildbot,google/skia-buildbot