[churn] Attempt to fix flaky StatusTrackerTest (#4347)

* attempt to fix flaky StatusTrackerTest

Error:  redis.clients.jedis.mcf.StatusTrackerTest.testWaitForHealthStatus_EventDriven -- Time elapsed: 0.130 s <<< FAILURE!
org.opentest4j.AssertionFailedError: Listener should have been registered ==> expected: not <null>
..
	at redis.clients.jedis.mcf.StatusTrackerTest.testWaitForHealthStatus_EventDriven(StatusTrackerTest.java:78)

* foramt

Author: ggivo

src/test/java/redis/clients/jedis/mcf/StatusTrackerTest.java

@@ -4,6 +4,7 @@
 import static org.mockito.Mockito.*;
 import static org.awaitility.Awaitility.await;
 
+import java.time.Duration;
 import java.util.concurrent.CountDownLatch;
 import java.util.concurrent.TimeUnit;
 import java.util.concurrent.atomic.AtomicReference;
@@ -71,11 +72,9 @@ void testWaitForHealthStatus_EventDriven() throws InterruptedException {
     });
     waitingThread.start();
 
-    // Give some time for the listener to be registered
-    Thread.sleep(50);
+    await().atMost(Duration.ofMillis(100L)).pollInterval(Duration.ofMillis(5L)).untilAsserted(
+      () -> assertNotNull(capturedListener[0], "Listener should have been registered"));
 
-    // Simulate health status change event
-    assertNotNull(capturedListener[0], "Listener should have been registered");
     HealthStatusChangeEvent event = new HealthStatusChangeEvent(testEndpoint, HealthStatus.UNKNOWN,
         HealthStatus.HEALTHY);
     capturedListener[0].onStatusChange(event);