Remove sleep when waiting for node closure

For each node in the cluster we were removing and then sleeping for
250ms.  There is an API that we can wait on to be sure the node has
closed or at least take action if the closure wasn't successful.

For the usage, which is cleaning up all nodes, switching to a best
effort mode that could wait the same 250ms or return faster.

Signed-off-by: Peter Nied <[email protected]>

src/test/java/org/opensearch/security/test/helper/cluster/ClusterHelper.java

@@ -39,6 +39,7 @@
 import java.util.SortedSet;
 import java.util.TreeSet;
 import java.util.concurrent.CountDownLatch;
+import java.util.concurrent.TimeUnit;
 import java.util.concurrent.atomic.AtomicReference;
 import java.util.stream.Collectors;
 
@@ -247,18 +248,18 @@ public final void stopCluster() throws Exception {
 
     private void closeAllNodes() throws  Exception {
         //close non master nodes
-        opensearchNodes.stream().filter(n->!n.isMasterEligible()).forEach(node->closeNode(node));
+        opensearchNodes.stream().filter(n->!n.isMasterEligible()).forEach(ClusterHelper::closeNode);
 
         //close master nodes
-        opensearchNodes.stream().filter(n->n.isMasterEligible()).forEach(node->closeNode(node));
+        opensearchNodes.stream().filter(n->n.isMasterEligible()).forEach(ClusterHelper::closeNode);
         opensearchNodes.clear();
         clusterState = ClusterState.STOPPED;
     }
 
     private static void closeNode(Node node) {
         try {
             node.close();
-            Thread.sleep(250);
+            node.awaitClose(250, TimeUnit.MILLISECONDS);
         } catch (Throwable e) {
             //ignore
         }