Disable terminal breadcrumbs by default (#38806)

<img width="1211" height="238" alt="image"
src="https://github.com/user-attachments/assets/d847fabe-0e00-474c-ad79-cb4da221b319"
/>

At least on Windows, "git terminal" and PowerShell set the header, which
is not very useful but occupies space and sometimes confuses users:


![telegram-cloud-photo-size-2-5377720447174575846-x](https://github.com/user-attachments/assets/a889fa44-e879-4b3d-956b-0af959113e1e)

Release Notes:

- Disable terminal breadcrumbs by default. Set
`terminal.toolbar.breadcrumbs` to `true` to re-enable.

Co-authored-by: Finn Evers <finn@zed.dev>

assets/settings/default.json

@@ -1432,7 +1432,7 @@
       //
       // The shell running in the terminal needs to be configured to emit the title.
       // Example: `echo -e "\e]2;New Title\007";`
-      "breadcrumbs": true
+      "breadcrumbs": false
     },
     // Scrollbar-related settings
     "scrollbar": {