message: network-grpc: don't use chained errors in Display impl for server::Error
  If an error handler displays or prints the error with chained error
  information obtained via Error trait, the messages should not be
  repeated.  The Display message also has a potential of growing
  indefinitely this way.
diff: @@ -169,10 +169,10 @@ where
  impl fmt::Display for Error {
  fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
  match self {
  - Error::Http2Handshake(e) => write!(f, "HTTP/2 handshake error: {}", e),
  - Error::Http2Protocol(e) => write!(f, "HTTP/2 protocol error: {}", e),
  - Error::NewService(e) => write!(f, "service creation error: {}", e),
  - Error::Service(e) => write!(f, "error returned by service: {}", e),
  + Error::Http2Handshake(_) => write!(f, "HTTP/2 handshake error"),
  + Error::Http2Protocol(_) => write!(f, "HTTP/2 protocol error"),
  + Error::NewService(_) => write!(f, "service creation error"),
  + Error::Service(_) => write!(f, "error returned by service"),
  Error::Execute => write!(f, "task execution error"),
  }
  }
  