ElasticV6QueryChangesTest: Close indices after test

For each test method, new indices are created with a unique name based
on the test method name. This results in 4 indices (i.e. one each for
accounts, changes, groups and projects) for each test method that is
run, which in turn results in the number of allocated shards increasing.

In Elasticsearch 7.0 a shard limit was introduced [1] which so far only
causes a warning. However in a future version the limit will be enforced
and result in an error.

After each test, close the indices that were created. This results in
the shards being deallocated, and prevents exceeding the limit.

Note that this was originally fixed in Change I6644cf9ee for ES 7.x
but the shard limit warning was backported to 6.x with [2] which was
included since 6.8.5, so we are now also seeing warnings in the logs
when running the tests for V6.

[1] https://www.elastic.co/guide/en/elasticsearch/reference/master/breaking-changes-7.0.html#_cluster_wide_shard_soft_limit
[2] https://github.com/elastic/elasticsearch/commit/aa8b5e8

Bug: Issue 10120
Change-Id: I61966c28c2640246e7a5edd026aa31d77c8533eb

javatests/com/google/gerrit/elasticsearch/ElasticV6QueryChangesTest.java

@@ -21,7 +21,12 @@ import com.google.gerrit.testing.InMemoryModule;
 import com.google.gerrit.testing.IndexConfig;
 import com.google.inject.Guice;
 import com.google.inject.Injector;
+import org.apache.http.client.methods.HttpPost;
+import org.apache.http.client.protocol.HttpClientContext;
+import org.apache.http.impl.nio.client.CloseableHttpAsyncClient;
+import org.apache.http.impl.nio.client.HttpAsyncClients;
 import org.eclipse.jgit.lib.Config;
+import org.junit.After;
 import org.junit.AfterClass;
 import org.junit.BeforeClass;
 
@@ -33,6 +38,7 @@ public class ElasticV6QueryChangesTest extends AbstractQueryChangesTest {
 
   private static ElasticNodeInfo nodeInfo;
   private static ElasticContainer container;
+  private static CloseableHttpAsyncClient client;
 
   @BeforeClass
   public static void startIndexService() {
@@ -43,6 +49,8 @@ public class ElasticV6QueryChangesTest extends AbstractQueryChangesTest {
 
     container = ElasticContainer.createAndStart(ElasticVersion.V6_8);
     nodeInfo = new ElasticNodeInfo(container.getHttpHost().getPort());
+    client = HttpAsyncClients.createDefault();
+    client.start();
   }
 
   @AfterClass
@@ -52,6 +60,16 @@ public class ElasticV6QueryChangesTest extends AbstractQueryChangesTest {
     }
   }
 
+  @After
+  public void closeIndex() {
+    client.execute(
+        new HttpPost(
+            String.format(
+                "http://localhost:%d/%s*/_close", nodeInfo.port, getSanitizedMethodName())),
+        HttpClientContext.create(),
+        null);
+  }
+
   @Override
   protected void initAfterLifecycleStart() throws Exception {
     super.initAfterLifecycleStart();