Remove unnecessary scrolling to MR notes

What does this MR do and why?

Fixes Thread navigation in Changes tab causes unneces... (#372267 - closed)

Screenshots or screen recordings

See the original issue for visual demonstration

How to set up and validate locally

1. Open a large MR (50+ files changed preferrable)
2. Go to the Changes tab
3. Create a new discussion in the middle of the page
4. Click on the discussion's date
5. Scroll to the end of the page
6. Slowly scroll up until you see the discussion

While scrolling top your scroll position should not be altered like in the original issue.

MR acceptance checklist

This checklist encourages us to confirm any changes have been analyzed to reduce risks in quality, performance, reliability, security, and maintainability.

• I have evaluated the MR acceptance checklist for this MR.