fix(server): Skip missed ticks instead of bursting in EWMA estimators

Tokio's default MissedTickBehavior::Burst fires catch-up ticks in
rapid succession after a delayed tick, making duration_since(last)
near-zero on catch-up iterations and inflating the rate estimate.
Skip is the right behavior for a rate estimator — recomputing stale
windows has no value.

Author: lcian

objectstore-server/src/rate_limits.rs

@@ -380,6 +380,7 @@ impl BandwidthRateLimiter {
         const TICK: Duration = Duration::from_millis(50); // Recompute EWMA on every TICK
 
         let mut interval = tokio::time::interval(TICK);
+        interval.set_missed_tick_behavior(tokio::time::MissedTickBehavior::Skip);
         // The first tick of a tokio interval fires immediately. Consume it so the
         // first real iteration has a full ~50ms of elapsed time.
         interval.tick().await;
@@ -558,6 +559,7 @@ impl ThroughputRateLimiter {
         tokio::task::spawn(async move {
             const TICK: Duration = Duration::from_millis(50);
             let mut interval = tokio::time::interval(TICK);
+            interval.set_missed_tick_behavior(tokio::time::MissedTickBehavior::Skip);
             interval.tick().await;
             let mut last = Instant::now();
             let mut global_ewma: f64 = 0.0;