Remove from the logs that a user was not rated in full privacy mode

[Catrya]

When a user is in full privacy mode and is rated (their counterpart doesn't know they are in that mode), this error appears in the logs because Mostro has no one to assign the rating to:

2025-04-16T15:09:55.011825Z  WARN mostrod::app: Error in RateUser with context Error in database access: Error caused by Error in database access: no rows returned by a query that expected to return at least one row

If someone runs a Mostro instance and sees this error, they may think something is wrong. Deleting that log completely prevents confusion, and it doesn't add much to having that information there.