the retry_writer retries parsing issues for syslog messages

[nicklas-dohrn]

due to the error propagation from the Writer to the retry_writer,
the call of msgs, err := w.syslogConverter.ToRFC5424(env, w.hostname)
can trigger a retry on a parsing issue, resulting in logs suggesting there where some connection issues, when the issue was indeed a parsing failure.
Retrying a parsing failure will also not resolve on retries, making the loop inefficient in this case.