Less severe log message for p2p server connection

Use the Warning level reporting errors for incoming protocol
connections, also change the message to refer to the connection
to avoid perception that it is the internal error of the server.

jormungandr/src/network/grpc/server.rs

@@ -50,9 +50,9 @@ pub fn run_listen_socket(
 
                     let conn = server.serve(stream);
                     let conn_logger = fold_logger.clone();
-                    tokio::spawn(
-                        conn.map_err(move |e| error!(conn_logger, "server error: {:?}", e)),
-                    );
+                    tokio::spawn(conn.map_err(move |e| {
+                        warn!(conn_logger, "incoming P2P connection error: {:?}", e)
+                    }));
 
                     future::ok(server)
                 })