[code_review] Use approved generated comments as examples

[suhaibmujahid]

Thought: we might want to mix comments written by developers and comments written by the bot (and accepted by developers). Perhaps it could be a number we can configure manually. This is a follow-up of course.

Originally posted by @marco-c in #4316 (comment)

[marco-c]

We should have a minimum similarity threshold for adding either bot or human comments as examples.