The new reviewers-by-blame plugin seems to work well, since libraryupgrader started getting added to reviews for changes that touch package.json. But it's not a human, and it can't provide reviews, so it should be exempted from the plugin somehow.
|All-Projects : refs/meta/config||reviewers-by-blame: default to not adding any reviewers|
|All-Projects : refs/meta/config||reviewers-by-blame: ignore build upgrades|
|Open||None||T214397 Gerrit: reviewers-by-blame plugin improvements|
|Open||Paladox||T213997 Exempt libraryupgrader from Gerrit's reviewers-by-blame plugin|
While build: upgrades probably shouldn't trigger adding reviewers in mass, the patch above does not achieve excluding libraryupgrader from being added to the list of reviewers. Apologies.
I have made the plugin to no more add any reviewers by default (done at All-Projects.git level). So you would no more get spam notifications.
This task is still relevant though, we would most certainly need a way for users to opt-out or blacklist some at the project level.