editor: Ensure placeholder text wraps properly after font size change (#37992)

Follow-up of https://github.com/zed-industries/zed/pull/37919

This fixes an issue where the placeholder text in editors would not wrap
properly in cases where the font size was changed.

Before:


https://github.com/user-attachments/assets/479c919f-5815-4164-b46d-75f31b5dc56f

After:


https://github.com/user-attachments/assets/9f63ab9f-eac2-4f3e-864c-2b96b58f2d71


Release Notes:

- N/A
d7f3d08c59Finn Evers committed on 9/11/2025, 1:20:05 PM· committed by GitHubparent4db19a3
1 file changedLine totals unavailable