[BHN] Onboard Chrome Desktop gardened builders onto builder health notifiers

This CL aims to onboard all builders owned by
chrome-desktop-engprod@google.com to builder health notifier. Builder
health notifier is a cron service part of lucy_notify. BHN will send out
a weekly summary of the health of builders, categorizing them as
healthy, unhealthy or unknown. More information on the code can be found
here - http://shortn/_9bN4k8qAgE.

This service will not send an email if all builders are healthy.

Health specs can be tweaked and are located here -
http://shortn/_rYqnv75zlj

Bug: 407539622
Change-Id: Iedcf15c2558bcbacbe85d38c38ee9d6ef0169369
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/6966098
Reviewed-by: Garrett Beaty <gbeaty@google.com>
Reviewed-by: Kuan Huang <kuanhuang@chromium.org>
Commit-Queue: Riley Wong <rgw@google.com>
Cr-Commit-Position: refs/heads/main@{#1519727}