[skcq] Add error rate alerts
[skcq] Add error rate alerts

Bug: skia:12053
Change-Id: I023c8843b8b3a6a7f92b7af029ba49fa5f9e437a
Reviewed-on: https://skia-review.googlesource.com/c/buildbot/+/429036
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