Move the file to shared and import it in two places.
This solution still requires the file to be duplicated. Solving this is more involved, as it would require storing this file in json format and importing it in lib, which currently isn't supported. Even if we use fs instead, we would still need to change the logic to be async.
https://linear.app/comm/issue/ENG-6780/share-reserved-usernames-between-services
Depends on D11015