HSEARCH-3759 Fix a bug in ElasticsearchIndexCreationAliasesIT

We shouldn't create the new index through the test client,
since the test is about checking that the backend creates
the index by itself.

integrationtest/backend/elasticsearch/src/test/java/org/hibernate/search/integrationtest/backend/elasticsearch/index/admin/ElasticsearchIndexCreationAliasesIT.java

@@ -108,8 +108,6 @@ public void migrationFrom6Beta4OrEarlier() {
 		elasticsearchClient.index( oldIndexName, null, null )
 				.deleteAndCreate()
 				.type().putMapping( simpleMappingForInitialization( "" ) );
-		elasticsearchClient.index( INDEX_NAME )
-				.deleteAndCreate();
 
 		setup( null );