Another discovery during search-on-type work.

Follow-up to https://github.com/zed-industries/zed/pull/19298 and
https://github.com/zed-industries/zed/pull/19846

With the `"soft_wrap": "editor_width"`, I should have no text contents
overflowing the editor width.

Before (scrollbar shown incorrectly):
<img width="2032" height="1162" alt="before"
src="https://github.com/user-attachments/assets/8b89ba6d-f98b-4ea0-89f2-8a22e968c438"
/>

After:
<img width="2032" height="1162" alt="after"
src="https://github.com/user-attachments/assets/93f62c2b-4981-48ae-aebd-8b0021348787"
/>


Release Notes:

- Fixed invisible symbol replacement width calculation