Stop/Start async search maintenance service in tests(#56673)

This change ensures that the maintenance service that is responsible for deleting the expired response is stopped between each test. This is needed since we check that no search context are in-flight after each test method.

Fixes #55988

x-pack/plugin/async-search/src/test/java/org/elasticsearch/xpack/search/AsyncSearchIntegTestCase.java

@@ -12,7 +12,10 @@
 import org.elasticsearch.action.admin.cluster.state.ClusterStateResponse;
 import org.elasticsearch.action.get.GetResponse;
 import org.elasticsearch.action.support.master.AcknowledgedResponse;
+import org.elasticsearch.cluster.ClusterChangedEvent;
+import org.elasticsearch.cluster.ClusterState;
 import org.elasticsearch.cluster.node.DiscoveryNode;
+import org.elasticsearch.common.component.Lifecycle;
 import org.elasticsearch.common.settings.Settings;
 import org.elasticsearch.common.unit.TimeValue;
 import org.elasticsearch.common.xcontent.ContextParser;
@@ -35,6 +38,7 @@
 import org.elasticsearch.xpack.core.XPackSettings;
 import org.elasticsearch.xpack.ilm.IndexLifecycle;
 import org.junit.After;
+import org.junit.Before;
 
 import java.io.Closeable;
 import java.util.Arrays;
@@ -72,6 +76,25 @@ public List<AggregationSpec> getAggregations() {
         }
     }
 
+    @Before
+    public void startMaintenanceService() {
+        for (AsyncSearchMaintenanceService service : internalCluster().getDataNodeInstances(AsyncSearchMaintenanceService.class)) {
+            if (service.lifecycleState() == Lifecycle.State.STOPPED) {
+                // force the service to start again
+                service.start();
+                ClusterState state = internalCluster().clusterService().state();
+                service.clusterChanged(new ClusterChangedEvent("noop", state, state));
+            }
+        }
+    }
+
+    @After
+    public void stopMaintenanceService() {
+        for (AsyncSearchMaintenanceService service : internalCluster().getDataNodeInstances(AsyncSearchMaintenanceService.class)) {
+            service.stop();
+        }
+    }
+
     @After
     public void releaseQueryLatch() {
         BlockingQueryBuilder.releaseQueryLatch();