assistant: Add tiny design tweaks to the patch block (#20636)

Adjusting really tiny things, most notably ensuring that the header text
doesn't overflow out of the block.

<img width="600" alt="Screenshot 2024-11-13 at 20 11 08"
src="https://github.com/user-attachments/assets/26656203-92c6-49e5-a732-bae010f96b2d">


Release Notes:

- N/A