[gold] remove alerts for non-k8s instances
[gold] remove alerts for non-k8s instances

These were ported to k8s and will be turned down.

NOTRY=true

Change-Id: I536c7e3f518e55fb2db6949a61625773443c97e2
Reviewed-on: https://skia-review.googlesource.com/c/buildbot/+/234910
Reviewed-by: Ravi Mistry <9fa2e7438b8cb730f96b74865492597170561628@google.com>
Commit-Queue: Ravi Mistry <9fa2e7438b8cb730f96b74865492597170561628@google.com>
Auto-Submit: Kevin Lubick <7cdab2cfab351f23814786ba39716e90eed69047@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