Use GString and closures to delay evaluating remote cluster URL until runtime

buildSrc/src/main/groovy/org/elasticsearch/gradle/test/ClusterConfiguration.groovy

@@ -96,15 +96,6 @@ class ClusterConfiguration {
         return seedNode.transportUri()
     }
 
-    /**
-     * A closure to call which returns a map of settings.
-     *
-     * This can be used to pass settings to a cluster that are not available at evaluation time ie.
-     * the address of a remote cluster etc.
-     */
-    @Input
-    Closure dynamicSettings = {  -> Collections.emptyMap() }
-
     /**
      * A closure to call before the cluster is considered ready. The closure is passed the node info,
      * as well as a groovy AntBuilder, to enable running ant condition checks. The default wait

buildSrc/src/main/groovy/org/elasticsearch/gradle/test/ClusterFormationTasks.groovy

@@ -294,8 +294,6 @@ class ClusterFormationTasks {
             if (unicastTransportUri != null) {
                 esConfig['discovery.zen.ping.unicast.hosts'] = "\"${unicastTransportUri}\""
             }
-            Map dynamicSettings = node.config.dynamicSettings();
-            esConfig.putAll(dynamicSettings)
             File configFile = new File(node.confDir, 'elasticsearch.yml')
             logger.info("Configuring ${configFile}")
             configFile.setText(esConfig.collect { key, value -> "${key}: ${value}" }.join('\n'), 'UTF-8')

qa/multi-cluster-search/build.gradle

@@ -35,10 +35,8 @@ task mixedClusterTest(type: RestIntegTestTask) {
   dependsOn(remoteClusterTest)
   cluster {
     distribution = 'zip'
-    dynamicSettings = {  ->
-      Collections.singletonMap("action.search.remote.my_remote_cluster",
-              "\"${remoteClusterTest.nodes.get(0).transportUri()}\"")
-    }
+    setting 'action.search.remote.my_remote_cluster', "\"${-> remoteClusterTest.nodes.get(0).transportUri()}\""
+
   }
   systemProperty 'tests.rest.suite', 'multi_cluster'
   finalizedBy 'remoteClusterTest#stop'