The `aws_s3` sink is logging `connection_closed_before_message_completed` errors

[binarylogic]

We're seeing reports from users that the aws_s3 sink is routinely logging connection_closed_before_message_completed errors, but the events_discarded_total metric is 0. They are also reporting that the large majority of events are being successfully written. We should look into this and...

• [ ] Ensure we are handling this error properly. If so, we should lower the log to trace level.
• [ ] Ensure data is not being dropped. If it is, discuss how this can be prevented and/or increment the events_discarded_total metric.

[fuchsnj]

There are several users reporting that this message is still being logged on 0.24.0 and 0.23.3