Enable online prewarming SPI in integration tests

Integration tests use the MockNode. This adds the SPI lookup
when building the MockSearchService. This will enable us to
have the online prewarming implementation avilable in
ESIntegTestCase.

Author: andreidan

test/framework/src/main/java/org/elasticsearch/node/MockNode.java

@@ -9,6 +9,8 @@
 
 package org.elasticsearch.node;
 
+import org.elasticsearch.action.search.OnlinePrewarmingService;
+import org.elasticsearch.action.search.OnlinePrewarmingServiceProvider;
 import org.elasticsearch.client.internal.node.NodeClient;
 import org.elasticsearch.cluster.ClusterInfoService;
 import org.elasticsearch.cluster.MockInternalClusterInfoService;
@@ -117,6 +119,10 @@ SearchService newSearchService(
                     tracer
                 );
             }
+            OnlinePrewarmingService onlinePrewarmingService = pluginsService.loadSingletonServiceProvider(
+                OnlinePrewarmingServiceProvider.class,
+                () -> OnlinePrewarmingServiceProvider.DEFAULT
+            ).create(clusterService.getSettings(), threadPool, clusterService);
             return new MockSearchService(
                 clusterService,
                 indicesService,
@@ -126,7 +132,8 @@ SearchService newSearchService(
                 fetchPhase,
                 circuitBreakerService,
                 executorSelector,
-                tracer
+                tracer,
+                onlinePrewarmingService
             );
         }
 

test/framework/src/main/java/org/elasticsearch/search/MockSearchService.java

@@ -85,7 +85,8 @@ public MockSearchService(
         FetchPhase fetchPhase,
         CircuitBreakerService circuitBreakerService,
         ExecutorSelector executorSelector,
-        Tracer tracer
+        Tracer tracer,
+        OnlinePrewarmingService onlinePrewarmingService
     ) {
         super(
             clusterService,
@@ -97,7 +98,7 @@ public MockSearchService(
             circuitBreakerService,
             executorSelector,
             tracer,
-            OnlinePrewarmingService.NOOP
+            onlinePrewarmingService
         );
     }