refactor(core): remove hotpath profiling (#2394)

hotpath adds noticeable overhead on hot paths, so remove the optional
profiling integration while keeping direct quanta::Instant timing.

easytier/src/connector/udp_hole_punch/cone.rs

@@ -1,7 +1,7 @@
 use std::{sync::Arc, time::Duration};
 
 use anyhow::Context;
-use hotpath::instant::Instant;
+use quanta::Instant;
 use tokio::net::UdpSocket;
 use tokio_util::task::AbortOnDropHandle;