UI breakdown of message of the last pushed branch for Create merge request

What does this MR do?

Fixes UI breakdown of message of the last pushed branch whose name is long around "Create merge request" button.

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

No.

Why was this MR needed?

To keep good enough UI design.

Screenshots (if relevant)

after fixed:

Cases	IMG	Notes
Long name		the main case
Short name		no regression confirmed

Does this MR meet the acceptance criteria?

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

What are the relevant issue numbers?

Closes #44382 (closed)