[BotService] Update Slack property (#19105)

* Add blockchain to latest profile

* Add additional types

* update slack property

Co-authored-by: Mark Cowlishaw <markcowl@microsoft.com>

Author: ssss141414

specification/botservice/resource-manager/Microsoft.BotService/preview/2021-05-01-preview/botservice.json

@@ -2378,8 +2378,7 @@
         },
         "registerBeforeOAuthFlow": {
           "type": "boolean",
-          "description": "Whether to register the settings before OAuth validation is performed. Recommended to True.",
-          "readOnly": true
+          "description": "Whether to register the settings before OAuth validation is performed. Recommended to True."
         },
         "IsValidated": {
           "type": "boolean",