Merge branch 'stable-2.15' into stable-2.16

* stable-2.15:
  ElasticContainer: Remove unneeded environment setting
  Remove redundant "testName" methods from Elasticsearch tests
  ElasticVersionTest: Add supportedVersion asserts for V7_0
  Add support for Elasticsearch 7
  Allow to set Elasticsearch number of shards and replicas
  Discontinue support for Elasticsearch 2.4.x
  ElasticSetting.Builder: Make methods return 'this'
  Add link to security documentation for Elasticsearch 6.5
  ElasticVersionTest: Add missing tests for 6.5.x

This merge also makes necessary changes related to the project index
which is not implemented on stable-2.15:

- Remove the tests for version 2.4.x
- Add tests for version 7

Change-Id: Id39158eb94aa71a8a5b22702ccc2009f4ce48b8c

javatests/com/google/gerrit/elasticsearch/ElasticV6QueryProjectsTest.java

@@ -52,10 +52,6 @@ public class ElasticV6QueryProjectsTest extends AbstractQueryProjectsTest {
     }
   }
 
-  private String testName() {
-    return testName.getMethodName().toLowerCase() + "_";
-  }
-
   @Override
   protected void initAfterLifecycleStart() throws Exception {
     super.initAfterLifecycleStart();
@@ -66,7 +62,7 @@ public class ElasticV6QueryProjectsTest extends AbstractQueryProjectsTest {
   protected Injector createInjector() {
     Config elasticsearchConfig = new Config(config);
     InMemoryModule.setDefaults(elasticsearchConfig);
-    String indicesPrefix = testName();
+    String indicesPrefix = getSanitizedMethodName();
     ElasticTestUtils.configure(elasticsearchConfig, nodeInfo.port, indicesPrefix);
     return Guice.createInjector(new InMemoryModule(elasticsearchConfig, notesMigration));
   }