Fix number of nodes in discovery disruption tests

This commit fixes the number of max local storage nodes setting used in
the discovery disruption tests. In some cases (randomly but rarely), the
acked indexing test can run with five nodes instead of three, breaching
the max local storage nodes configuration.

core/src/test/java/org/elasticsearch/discovery/DiscoveryWithServiceDisruptionsIT.java

@@ -208,7 +208,7 @@ public class DiscoveryWithServiceDisruptionsIT extends ESIntegTestCase {
         // TODO: Rarely use default settings form some of these
         Settings nodeSettings = Settings.builder()
                 .put(settings)
-                .put(NodeEnvironment.MAX_LOCAL_STORAGE_NODES_SETTING.getKey(), 4)
+                .put(NodeEnvironment.MAX_LOCAL_STORAGE_NODES_SETTING.getKey(), numberOfNodes)
                 .put(ElectMasterService.DISCOVERY_ZEN_MINIMUM_MASTER_NODES_SETTING.getKey(), minimumMasterNode)
                 .build();