test: replace Thread.sleep with sync primitives in tests

Replace flaky Thread.sleep calls with proper synchronization:

- SharedProcessorTest: use Semaphore(0).acquire() instead of
  Thread.sleep(10s) so the worker blocks until interrupted by
  shutdownNow(), making the test deterministic and instant.

- KubernetesReconcilerCreatorTest: use Wait.poll() instead of
  Thread.sleep(500ms) to actively poll until the work queue is
  populated, making the test faster and non-flaky.

Addresses part of #1223.

Co-Authored-By: Oz <oz-agent@warp.dev>

Author: emmaeng700

spring/src/test/java/io/kubernetes/client/spring/extended/controller/KubernetesReconcilerCreatorTest.java

@@ -22,6 +22,7 @@
 import io.kubernetes.client.extended.controller.reconciler.Reconciler;
 import io.kubernetes.client.extended.controller.reconciler.Request;
 import io.kubernetes.client.extended.controller.reconciler.Result;
+import io.kubernetes.client.extended.wait.Wait;
 import io.kubernetes.client.extended.workqueue.WorkQueue;
 import io.kubernetes.client.informer.SharedInformer;
 import io.kubernetes.client.informer.SharedInformerFactory;
@@ -46,6 +47,7 @@
 import io.kubernetes.client.spring.extended.controller.annotation.UpdateWatchEventFilter;
 import io.kubernetes.client.spring.extended.controller.factory.KubernetesControllerFactory;
 import io.kubernetes.client.util.ClientBuilder;
+import java.time.Duration;
 import java.util.LinkedList;
 import java.util.function.Function;
 import jakarta.annotation.Resource;
@@ -194,9 +196,10 @@ void simplePodController() throws InterruptedException {
               }
             });
 
-    Thread.sleep(500);
-
     WorkQueue<Request> workQueue = ((DefaultController) testController).getWorkQueue();
+    boolean itemAdded =
+        Wait.poll(Duration.ofMillis(10), Duration.ofSeconds(5), () -> workQueue.length() >= 1);
+    assertThat(itemAdded).isTrue();
     assertThat(workQueue.length()).isEqualTo(1);
     assertThat(workQueue.get().getName()).isEqualTo("foo");
     sharedInformerFactory.stopAllRegisteredInformers();

util/src/test/java/io/kubernetes/client/informer/cache/SharedProcessorTest.java

@@ -21,6 +21,7 @@
 import java.time.Duration;
 import java.util.concurrent.CountDownLatch;
 import java.util.concurrent.Executors;
+import java.util.concurrent.Semaphore;
 import org.junit.jupiter.api.Test;
 
 class SharedProcessorTest {
@@ -69,11 +70,12 @@ void shutdownGracefully() throws InterruptedException {
     TestWorker<V1Pod> slowWorker = new TestWorker<>(null, 0);
     final boolean[] interrupted = {false};
     CountDownLatch latch = new CountDownLatch(1);
+    Semaphore blocker = new Semaphore(0);
     slowWorker.setTask(
         () -> {
           try {
-            // sleep 10s so that it could be interrupted by shutdownNow()
-            Thread.sleep(10 * 1000);
+            // block until interrupted by shutdownNow()
+            blocker.acquire();
           } catch (InterruptedException e) {
             interrupted[0] = true;
           } finally {