Clean up various avatar dimensions (#24701)

Clean up various avatar dimensions (#24701)

Clean up a few cases where avatar dimensions were overwritten via CSS,
which were no longer needed or were possible to set via HTML width.

Also included are two small fixes:

- Fix one more case of incorrect avatar offset on review timeline
- Vertically center avatars in review sidebar

There is more to be done here, but some of the work depends on Fomantic
`comment` module removal, or in the case of org member lists, a refactor
of the `avatarlink` template to accept a size.

<img width="371" alt="image"
src="https://github.com/go-gitea/gitea/assets/115237/9c5902fb-2b89-4a7d-a152-60e74c3b2c56">
<img width="306" alt="image"
src="https://github.com/go-gitea/gitea/assets/115237/c8d92e2a-91c9-4f4a-a7de-6ae1a6bc0479">

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Co-authored-by: Giteabot <teabot@gitea.io>