Show author avatars when commit rapid diffs discussions are hidden

The following discussion from !215315 should be addressed:

• @mle started a discussion: (+1 comment)

  @ms.mondrian @slashmanov question when comments are collapsed in merge requests we show the avatar of the commenter in the gutter area, is it possible to do the same for commits?

  CleanShot_2025-12-10_at_00.34.24

  Eventually we should be without it there is no feedback that there are comments on the diff. I am open to when you would want to tackle this as part of this MR or a follow up.