Revert "Support for Embeded chat (#9129)" (#10017)

This reverts commit 3fcecd521a.

config/default.json

@@ -203,10 +203,6 @@
         "LoginButtonBorderColor": "",
         "LoginButtonTextColor": ""
     },
-    "ExtensionSettings": {
-        "EnableExperimentalExtensions": false,
-        "AllowedExtensionsIDs": []
-    },
     "RateLimitSettings": {
         "Enable": false,
         "PerSec": 10,