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>

docs/src/configuring-zed.md

@@ -3520,7 +3520,7 @@ List of `integer` column numbers
     "button": true,
     "shell": "system",
     "toolbar": {
-      "breadcrumbs": true
+      "breadcrumbs": false
     },
     "working_directory": "current_project_directory",
     "scrollbar": {
@@ -3941,7 +3941,7 @@ Disable with:
 {
   "terminal": {
     "toolbar": {
-      "breadcrumbs": true
+      "breadcrumbs": false
     }
   }
 }