message: Lower proxy connection errors to debug level
diff: @@ -508,9 +508,11 @@ async fn connect_proxy_server(context: &Context, svr_cfg: &ServerConfig) -> io::
  }
  Err(err) => {
  // Connection failure, retry
  - debug!(
  + trace!(
  "failed to connect {}, retried {} times (last err: {})",
  - svr_addr, retry_time, err
  + svr_addr,
  + retry_time,
  + err
  );
  last_err = Some(err);
  @@ -523,7 +525,7 @@ async fn connect_proxy_server(context: &Context, svr_cfg: &ServerConfig) -> io::
  }
  let last_err = last_err.unwrap();
  - error!(
  + debug!(
  "failed to connect {}, retried {} times, last_err: {}",
  svr_addr, RETRY_TIMES, last_err
  );
  