Weird jump when leaving a comment on a Merge Request Diff

Related to #340896 (closed).

Problem

Weird scrolling when clicking to leave a comment.

I received a bug complaint from a director at https://gitlab.my.salesforce.com/00161000004zoB7 that I believe is captured by this issue.

In their team, code reviews with somewhat large diffs (in the hundreds of lines across dozens of files) are very common, and the indeterminate scrolling when attempting to add a comment/suggestion in an MR is very disorienting and time consuming.

While I cannot share a recording of their experience, it was easily reproduced in a test project, see https://gitlab.com/jrreid/pages-large-mr-example/-/merge_requests/1.

See attached screen recording for an example of the "jumping" scrolling behavior.

(...)

recording-out in #340896 (comment 813048210) by @jrreid

Steps to reproduce

1. • Go to: gitlab-org/opstrace/opstrace!1634 (diffs)
2. • Close file tree and refresh page (to ensure that the file tree is closed when navigating to the page)
3. • Open file tree
4. • Scroll down the file tree and click on the role.yaml
5. • Click to leave a comment in role.yaml
6. • Comment dialog is open but browser scrolls to the top of the page

Further info

While the overall topic of rendering diffs with large files continues to be addressed in #340896 (closed) and &6497 (closed) we'll track this immediate bug fix in this issue