Fix diagnostic popover not overflowing when necessary (#14322)

It was broken after #13996 moved rendering text one level deeper,
causing `max_h` and `overflow_y_scroll` to apply to different widgets
Release Notes:

- Fixed large diagnostic popovers not overflowing when nessesary

Before:
<img width="814" alt="Screenshot 2024-07-12 at 15 25 46"
src="https://github.com/user-attachments/assets/4f615600-2857-4470-8b77-864e3a9e38d5">

After:
<img width="813" alt="Screenshot 2024-07-12 at 15 26 10"
src="https://github.com/user-attachments/assets/83c1f344-b3b1-4929-8197-4b24a0e9c65e">