Fix Netty 4 multi-port test

This commit fixes an issue with the Netty 4 multi-port test that a
transport client can connect. The problem here is that in case the
bottom of the random port range was already bound to (for example, by
another JVM) then then transport client could not connect to the data
node. This is because the transport client was in fact using the bottom
of the port range only. Instead, we simply try all the ports that the
data node might be bound to.

This commit is cherry picked from 049e641 but adapted to preserve the
use of InetSocketTransportAddress

Closes #24441

Author: jasontedor

modules/transport-netty4/src/test/java/org/elasticsearch/transport/netty4/Netty4TransportMultiPortIntegrationIT.java

@@ -58,7 +58,7 @@ public class Netty4TransportMultiPortIntegrationIT extends ESNetty4IntegTestCase
     protected Settings nodeSettings(int nodeOrdinal) {
         if (randomPort == -1) {
             randomPort = randomIntBetween(49152, 65525);
-            randomPortRange = String.format(Locale.ROOT, "%s-%s", randomPort, randomPort+10);
+            randomPortRange = String.format(Locale.ROOT, "%s-%s", randomPort, randomPort + 10);
         }
         Settings.Builder builder = Settings.builder()
             .put(super.nodeSettings(nodeOrdinal))
@@ -76,8 +76,12 @@ public void testThatTransportClientCanConnect() throws Exception {
             .put(NetworkModule.TRANSPORT_TYPE_KEY, Netty4Plugin.NETTY_TRANSPORT_NAME)
             .put(Environment.PATH_HOME_SETTING.getKey(), createTempDir().toString())
             .build();
+        // we have to test all the ports that the data node might be bound to
         try (TransportClient transportClient = new MockTransportClient(settings, Netty4Plugin.class)) {
             transportClient.addTransportAddress(new InetSocketTransportAddress(InetAddress.getByName("127.0.0.1"), randomPort));
+            for (int i = 0; i <= 10; i++) {
+                transportClient.addTransportAddress(new InetSocketTransportAddress(InetAddress.getByName("127.0.0.1"), randomPort + i));
+            }
             ClusterHealthResponse response = transportClient.admin().cluster().prepareHealth().get();
             assertThat(response.getStatus(), is(ClusterHealthStatus.GREEN));
         }