Overload errors from the ingress request rate limiter should include the NoWritesPerformed error label. NoWritesPerformed was originally added in DRIVERS-2327. With client backpressure there's a similar scenario where NoWritesPerformed is needed:

• Client sends a retryable write
• Client sees a RetryableWriteError (either from the server or a network error) and runs a retry attempt.
• All retry attempts fail with SystemOverloadedError but without NoWritesPerformed.
• Client fails with SystemOverloadedError which implies the write was definitely not applied which is incorrect.

When the server attaches NoWritesPerformed, the client will correctly reraise the first RetryableWriteError which indicates that the result is not known.