disable sampling in testNotifyOnDisconnect

the background activity confuses the test

core/src/test/java/org/elasticsearch/client/transport/NodeDisconnectIT.java

@@ -24,28 +24,30 @@ import org.elasticsearch.common.transport.TransportAddress;
 import org.elasticsearch.test.ESIntegTestCase;
 import org.elasticsearch.transport.MockTransportClient;
 import org.elasticsearch.transport.TransportService;
-import org.hamcrest.Matchers;
 
 import java.io.IOException;
 import java.util.Collections;
 import java.util.HashSet;
-import java.util.List;
 import java.util.Set;
-import java.util.stream.Collector;
 import java.util.stream.Collectors;
 
+import static org.elasticsearch.client.transport.TransportClient.CLIENT_TRANSPORT_NODES_SAMPLER_INTERVAL;
+
 public class NodeDisconnectIT  extends ESIntegTestCase {
 
-    public void testNotifyOnDisconnect() throws IOException {
+    public void testNotifyOnDisconnect() throws IOException, InterruptedException {
         internalCluster().ensureAtLeastNumDataNodes(2);
 
         final Set<DiscoveryNode> disconnectedNodes = Collections.synchronizedSet(new HashSet<>());
         try (TransportClient client = new MockTransportClient(Settings.builder()
-            .put("cluster.name", internalCluster().getClusterName()).build(), Collections.emptySet(), (n, e) -> disconnectedNodes.add(n))) {
+            .put("cluster.name", internalCluster().getClusterName())
+            .put(CLIENT_TRANSPORT_NODES_SAMPLER_INTERVAL.getKey(), "1h") // disable sniffing for better control
+            .build(),
+            Collections.emptySet(), (n, e) -> disconnectedNodes.add(n))) {
             for (TransportService service : internalCluster().getInstances(TransportService.class)) {
                 client.addTransportAddress(service.boundAddress().publishAddress());
             }
-            internalCluster().stopRandomDataNode();
+            internalCluster().stopCurrentMasterNode();
             for (int i = 0; i < 20; i++) { // fire up requests such that we hit the node and pass it to the listener
                 client.admin().cluster().prepareState().get();
             }