feat: if Adminlog is null, don't log to stderr either — radicle-ci-broker

Signed-off-by: Lars Wirzenius liw@liw.fi

                 #[allow(clippy::unwrap_used)] // we know it's OK
                 file.write_all(msg.as_bytes())
                     .map_err(|e| LogError::WriteLogFile(self.filename.clone().unwrap(), e))?;
             } else {
                 eprintln!("ambient adapter: {msg}");
             }
             Ok(())
         }