Function rskafka_client_error_to_retry_hint 

pub fn rskafka_client_error_to_retry_hint(error: &Error) -> RetryHint

Maps an rskafka client error to a conservative retry hint.

rskafka already retries most transient Kafka/network errors internally. This helper only marks errors retryable when rskafka has exhausted its own retry loop or returns an explicit client timeout.