🐛 Fix return value in create_user_pre_registration and remove unused import in _users_rest

Author: pcrespov

services/web/server/src/simcore_service_webserver/users/_users_repository.py

@@ -437,7 +437,8 @@ async def create_user_pre_registration(
             )
             .returning(users_pre_registration_details.c.id)
         )
-        return result.scalar_one()
+        pre_registration_id: int = result.scalar_one()
+        return pre_registration_id
 
 
 async def get_user_billing_details(

services/web/server/src/simcore_service_webserver/users/_users_rest.py

@@ -1,6 +1,5 @@
 import logging
 from contextlib import suppress
-from itertools import product
 
 from aiohttp import web
 from models_library.api_schemas_webserver.users import (