Stop invidual nodes and get node names in test clusters (#97402)

Adds
`public String getName(int index)`
`public void stopNode(int index)`

To the cluster handle.

Author: stu-elastic

test/test-clusters/src/main/java/org/elasticsearch/test/cluster/ClusterHandle.java

@@ -29,6 +29,12 @@ public interface ClusterHandle extends Closeable {
      */
     void stop(boolean forcibly);
 
+    /**
+     * Stops the node at a given index.
+     * @param index of the node to stop
+     */
+    void stopNode(int index);
+
     /**
      * Restarts the cluster. Effectively the same as calling {@link #stop(boolean)} followed by {@link #start()}
      *
@@ -60,6 +66,11 @@ public interface ClusterHandle extends Closeable {
      */
     String getHttpAddress(int index);
 
+    /**
+     * Get the name of the node for the given index.
+     */
+    String getName(int index);
+
     /**
      * Returns a comma-separated list of TCP transport endpoints for cluster. If this method is called on an unstarted cluster, the cluster
      * will be started. This method is thread-safe and subsequent calls will wait for cluster start and availability.

test/test-clusters/src/main/java/org/elasticsearch/test/cluster/DefaultElasticsearchCluster.java

@@ -53,6 +53,12 @@ public void stop(boolean forcibly) {
         handle.stop(forcibly);
     }
 
+    @Override
+    public void stopNode(int index) {
+        checkHandle();
+        handle.stopNode(index);
+    }
+
     @Override
     public void restart(boolean forcibly) {
         checkHandle();
@@ -83,6 +89,12 @@ public String getHttpAddress(int index) {
         return handle.getHttpAddress(index);
     }
 
+    @Override
+    public String getName(int index) {
+        checkHandle();
+        return handle.getName(index);
+    }
+
     @Override
     public String getTransportEndpoints() {
         checkHandle();

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

@@ -156,6 +156,14 @@ public void upgradeToVersion(Version version) {
         waitUntilReady();
     }
 
+    public String getName(int index) {
+        return nodes.get(index).getName();
+    }
+
+    public void stopNode(int index) {
+        nodes.get(index).stop(false);
+    }
+
     protected void waitUntilReady() {
         writeUnicastHostsFile();
         try {