Remove assistant hints (#21171)

This reverts #20824 and #20899. After adding them last week we came to
the conclusion that the hints are too distracting in everyday use, see
#21128 for more details.

Release Notes:

- N/A

docs/src/configuring-zed.md

@@ -2333,18 +2333,15 @@ Run the `theme selector: toggle` action in the command palette to see a current
 - Default:
 
 ```json
-{
-  "assistant": {
-    "enabled": true,
-    "button": true,
-    "dock": "right",
-    "default_width": 640,
-    "default_height": 320,
-    "provider": "openai",
-    "version": "1",
-    "show_hints": true
-  }
-}
+"assistant": {
+  "enabled": true,
+  "button": true,
+  "dock": "right",
+  "default_width": 640,
+  "default_height": 320,
+  "provider": "openai",
+  "version": "1",
+},
 ```
 
 ## Outline Panel