[alert-manager] Use new Infra Gardener endpoint in frontend
[alert-manager] Use new Infra Gardener endpoint in frontend

And replace "trooper" with "infra gardener" in am frontend code.

Bug: skia:11034
Change-Id: I464ca34d052d4c173df6888d2b5805668003ffe9
Reviewed-on: https://skia-review.googlesource.com/c/buildbot/+/346439
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