Remove network settings when security is disabled

When security is disabled, we currently set the transport and HTTP type
to Netty 4. However, this is unnecessary as these are the default
settings so this commit removes these explicit settings.

Relates elastic/elasticsearch#3065

Original commit: elastic/x-pack-elasticsearch@afa360ceec

elasticsearch/x-pack/security/src/main/java/org/elasticsearch/xpack/security/Security.java

@@ -338,10 +338,7 @@ public class Security implements ActionPlugin, IngestPlugin {
 
     public Settings additionalSettings() {
         if (enabled == false) {
-            return Settings.builder()
-                    .put(NetworkModule.HTTP_TYPE_KEY, "netty4")
-                    .put(NetworkModule.TRANSPORT_TYPE_KEY, "netty4")
-                    .build();
+            return Settings.EMPTY;
         }
 
         return additionalSettings(settings);