Enable online prewarming SPI in integration tests (elastic#126777)

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
         );
     }