Tweak pull request branch delete ui (#23951)
- Move delete button to right and remove red color on it.
- Remove CLI instructions when PR has been merged.
Before:
<img width="855" alt="Screenshot 2023-04-06 at 20 21 47"
src="https://user-images.githubusercontent.com/115237/230463178-95735fc0-9632-4d51-bbd5-2131c40186c4.png">
After:
<img width="865" alt="Screenshot 2023-04-06 at 20 23 17"
src="https://user-images.githubusercontent.com/115237/230463347-8155cbf9-4e58-421a-93a8-56ce6188dab8.png">
After (deleted):
<img width="860" alt="Screenshot 2023-04-06 at 20 19 30"
src="https://user-images.githubusercontent.com/115237/230463442-f53d7500-191d-4d75-a097-d100a461672a.png">
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Co-authored-by: Giteabot <teabot@gitea.io>
