Resolve "Right column of merge request discussion overflows"

What does this MR do?

Fixes the overflow of discussion timestamps in merge request parallel viewing mode

Are there points in the code the reviewer needs to double check?

None in the code, but it should perhaps be reviewed by UX if it's okay that the timestamp wraps to an additional line in the inline viewing mode:

Before (white-space: nowrap)

After (white-space: normal)

Why was this MR needed?

Because the overflow of text detracts from our UX.

Screenshots (if relevant)

Before

After

Does this MR meet the acceptance criteria?

• Changelog entry added, if necessary
• Documentation created/updated
• API support added
• Tests added for this feature/bug
• Review
  • Has been reviewed by UX
  • Has been reviewed by Frontend
  • Has been reviewed by Backend
  • Has been reviewed by Database
• Conform by the merge request performance guides
• Conform by the style guides
• Squashed related commits together
• Internationalization required/considered
• End-to-end tests pass (package-qa manual pipeline job)

What are the relevant issue numbers?

Closes #39521 (closed)