Fixed DefaultSettingsProvider to use Java 17 (elastic#116029)

It is needed to be able to backport the change to the 8.x.
Having same code for both versions can help us to avoid some merge
conflicts in the future.

Author: jozala

test/test-clusters/src/main/java/org/elasticsearch/test/cluster/local/DefaultSettingsProvider.java

@@ -95,9 +95,6 @@ public Map<String, String> get(LocalNodeSpec nodeSpec) {
 
     private boolean isMultiNodeCluster(LocalClusterSpec cluster) {
         return cluster.getNodes().size() > 1
-            || cluster.getNodes()
-                .getFirst()
-                .getSetting(DISCOVERY_TYPE_SETTING, MULTI_NODE_DISCOVERY_TYPE)
-                .equals(MULTI_NODE_DISCOVERY_TYPE);
+            || cluster.getNodes().get(0).getSetting(DISCOVERY_TYPE_SETTING, MULTI_NODE_DISCOVERY_TYPE).equals(MULTI_NODE_DISCOVERY_TYPE);
     }
 }