refactor: delay initial sync trigger

Don't immediately dispatch a consistency probe when the router starts
up, when it may be under higher initial load.

router/src/gossip/anti_entropy/sync/actor.rs

@@ -175,6 +175,8 @@ where
  // Wait at least SYNC_ROUND_INTERVAL between consistency checks.
  ticker.set_missed_tick_behavior(tokio::time::MissedTickBehavior::Delay);
 
+ let _ = ticker.tick().await;
+
  loop {
  tokio::select! {
  _ = ticker.tick() =>
@@ -313,15 +315,17 @@ mod tests {
 
  // Wait for a probe to happen.
  let mut calls = async {
- loop {
+ for _ in 0..100 {
+ tokio::time::pause();
  let calls = consistency_prober.calls();
  if !calls.is_empty() {
  return calls;
  }
+ tokio::time::resume();
  tokio::time::sleep(Duration::from_millis(50)).await;
  }
+ panic!("timeout");
  }
- .with_timeout_panic(Duration::from_secs(5))
  .await;
 
  // It's technically possible that multiple probes could have been sent