Remove remaining shortcut to focus the chat input (#1186)

Author: brichet

packages/jupyter-ai/schema/plugin.json

@@ -4,14 +4,6 @@
   "description": "JupyterLab generative artificial intelligence integration.",
   "jupyter.lab.setting-icon": "jupyter-ai::chat",
   "jupyter.lab.setting-icon-label": "Jupyter AI Chat",
-  "jupyter.lab.shortcuts": [
-    {
-      "command": "jupyter-ai:focus-chat-input",
-      "keys": ["Accel Shift 1"],
-      "selector": "body",
-      "preventDefault": false
-    }
-  ],
   "jupyter.lab.menus": {
     "main": [
       {