In the api docs note that `silence_reason` and `can_be_deleted` are
optional responses for the admin user api response.
Follow up to: 9cf78ba195506ba5d76c9e5234d6a74e66001e29
> TODO @blake / @sam - this is not passing cause "silence_reason" is a conditional attribute
> (also can_be_deleted is) - we need to figure out how to not include it in the schema - it is not included
> in the admin response by design
6811296b24