Cleanup BK for each test

pulsar-broker/src/test/java/org/apache/pulsar/broker/loadbalance/extensions/ExtensibleLoadManagerCloseTest.java

@@ -42,11 +42,12 @@
 public class ExtensibleLoadManagerCloseTest {
 
     private static final String clusterName = "test";
-    private final LocalBookkeeperEnsemble bk = new LocalBookkeeperEnsemble(1, 0, () -> 0);
     private final List<PulsarService> brokers = new ArrayList<>();
+    private LocalBookkeeperEnsemble bk;
 
     @BeforeClass(alwaysRun = true)
     public void setup() throws Exception {
+        bk = new LocalBookkeeperEnsemble(1, 0, () -> 0);
         bk.start();
     }