Fix ReloadSynonymAnalyzerIT failure (#53663) (#53806)

There is an assertion in ReloadAnalyzersResponse.merge that compares index names
of merged responses that was falsely using object equality instead of
String.equals(). In the past this didn't seem to matter but with changes in the
test setup we started to see failures. Correcting this and also simplifying test
a bit to be able to run it repeatedly if needed.

Backport of #53663

x-pack/plugin/core/src/main/java/org/elasticsearch/xpack/core/action/ReloadAnalyzersResponse.java

@@ -164,7 +164,7 @@ public class ReloadAnalyzersResponse extends BroadcastResponse  {
         }
 
         void merge(ReloadResult other) {
-            assert this.indexName == other.index;
+            assert this.indexName.equals(other.index);
             this.reloadedAnalyzers.addAll(other.reloadedSearchAnalyzers);
             this.reloadedIndicesNodes.add(other.nodeId);
         }

x-pack/plugin/core/src/test/java/org/elasticsearch/xpack/core/rest/action/ReloadSynonymAnalyzerIT.java

@@ -5,7 +5,6 @@
  */
 package org.elasticsearch.xpack.core.rest.action;
 
-import org.apache.lucene.util.LuceneTestCase;
 import org.elasticsearch.action.admin.indices.analyze.AnalyzeAction.AnalyzeToken;
 import org.elasticsearch.action.admin.indices.analyze.AnalyzeAction.Response;
 import org.elasticsearch.action.search.SearchResponse;
@@ -40,7 +39,6 @@ import static org.elasticsearch.test.hamcrest.ElasticsearchAssertions.assertAcke
 import static org.elasticsearch.test.hamcrest.ElasticsearchAssertions.assertHitCount;
 import static org.elasticsearch.test.hamcrest.ElasticsearchAssertions.assertNoFailures;
 
-@LuceneTestCase.AwaitsFix(bugUrl = "https://github.com/elastic/elasticsearch/issues/53443")
 public class ReloadSynonymAnalyzerIT extends ESIntegTestCase {
 
     @Override
@@ -48,11 +46,24 @@ public class ReloadSynonymAnalyzerIT extends ESIntegTestCase {
         return Settings.builder().put(super.nodeSettings(nodeOrdinal)).put(XPackSettings.SECURITY_ENABLED.getKey(), false).build();
     }
 
+    @Override
+    protected Settings transportClientSettings() {
+        return Settings.builder().put(XPackSettings.SECURITY_ENABLED.getKey(), false).build();
+    }
+
     @Override
     protected Collection<Class<? extends Plugin>> nodePlugins() {
         return Arrays.asList(LocalStateCompositeXPackPlugin.class, CommonAnalysisPlugin.class);
     }
 
+    /**
+     * Returns a collection of plugins that should be loaded when creating a transport client.
+     */
+    @Override
+    protected Collection<Class<? extends Plugin>> transportClientPlugins() {
+        return Arrays.asList(LocalStateCompositeXPackPlugin.class);
+    }
+
     /**
      * This test needs to write to the config directory, this is difficult in an external cluster so we overwrite this to force running with
      * {@link InternalTestCluster}
@@ -66,10 +77,8 @@ public class ReloadSynonymAnalyzerIT extends ESIntegTestCase {
         Path config = internalCluster().getInstance(Environment.class).configFile();
         String synonymsFileName = "synonyms.txt";
         Path synonymsFile = config.resolve(synonymsFileName);
-        Files.createFile(synonymsFile);
-        assertTrue(Files.exists(synonymsFile));
         try (PrintWriter out = new PrintWriter(
-                new OutputStreamWriter(Files.newOutputStream(synonymsFile, StandardOpenOption.CREATE), StandardCharsets.UTF_8))) {
+                new OutputStreamWriter(Files.newOutputStream(synonymsFile), StandardCharsets.UTF_8))) {
             out.println("foo, baz");
         }
         assertAcked(client().admin().indices().prepareCreate("test").setSettings(Settings.builder()