Reports should try to tag `@brave-core-owners` whenever possible

As the description says. Notice that there is a chromium group called @brave-core-owners, and using that when for rules where only 2 members of the group occur may suffice. It can be discussed better during code review.

The issue names no file, test, or entry point. Start by locating the report-tagging logic and determine how rules with only two matching members should use @brave-core-owners; code review must settle the expected behavior, and done means reports tag that group whenever possible.

Written by the indexing model from the issue text.