fix(types): Validate groupId in installation external issue actions

Add validation to ensure groupId is provided in request data, returning
400 error if missing before querying the Group model.

Author: JoshFerge

src/sentry/sentry_apps/api/endpoints/installation_external_issue_actions.py

@@ -57,6 +57,8 @@ def post(self, request: Request, installation) -> Response:
             return Response(external_issue_action_serializer.errors, status=400)
 
         group_id = data.get("groupId")
+        if not group_id:
+            return Response({"groupId": ["This field is required"]}, status=400)
         del data["groupId"]
 
         try: