x/build/cmd/gerritbot: don't post CL updates if the PR author has a Gerrit account

[mvdan]

For example: #23809

If gerritbot successfully added the PR author as a reviewer or as CC to the Gerrit CL, it makes little sense to forward comment/review updates to the Github pull request in the form of comments.

[bradfitz]

I also suspect we'll need some fancier GitHub email <-> Gerrit email mapping at some point. A good percentage of users have different emails in their Git Author lines vs their Gerrit (Google) account.

[mvdan]

It also seems a bit too spammy if a CL is very active. Assuming that the purpose of these comments is to keep the author notified, I think we should limit them to one per day.

Would also be interesting to not notify about a comment that the author themselves posted, but that seems tricky. If we knew who the author was on Gerrit, we wouldn't be posting the notifications to begin with.

[andybons]

It also seems a bit too spammy if a CL is very active. Assuming that the purpose of these comments is to keep the author notified, I think we should limit them to one per day.

It’s unlikely we will implement a digest. This is the exact reason /comments off exists (plus GitHub has its own notification settings).

Agreed that it should default to comments off if the author is also getting emailed in Gerrit.