Stop posting go/dart-cbuild comments on Gerrit

It is now redundant, e.g. https://dart-review.googlesource.com/c/sdk/+/357920/4#message-f0c33a7ae5f71e06f27a9bbefdcdb019ff5d5c88

Bug: b/294808886
Change-Id: I53e547c5591062acd5652dd75b136e586c62373c
Reviewed-on: https://dart-review.googlesource.com/c/recipes/+/358441
Reviewed-by: Alexander Thomas <athom@google.com>
Commit-Queue: Alexander Thomas <athom@google.com>
Auto-Submit: Oleh Prypin <oprypin@google.com>
3 files changed