[router] Add rustfmt and set group imports by default (#11732)

sgl-router/src/core/circuit_breaker.rs

@@ -1,6 +1,11 @@
-use std::sync::atomic::{AtomicU32, AtomicU64, Ordering};
-use std::sync::{Arc, RwLock};
-use std::time::{Duration, Instant};
+use std::{
+    sync::{
+        atomic::{AtomicU32, AtomicU64, Ordering},
+        Arc, RwLock,
+    },
+    time::{Duration, Instant},
+};
+
 use tracing::info;
 
 /// Circuit breaker configuration
@@ -316,9 +321,10 @@ pub struct CircuitBreakerStats {
 
 #[cfg(test)]
 mod tests {
-    use super::*;
     use std::thread;
 
+    use super::*;
+
     #[test]
     fn test_circuit_breaker_initial_state() {
         let cb = CircuitBreaker::new();