HSEARCH-4152 Avoid to use *Settings constants

So that it is clearer the target property here

integrationtest/backend/elasticsearch/src/test/java/org/hibernate/search/integrationtest/backend/elasticsearch/schema/management/ElasticsearchIndexSchemaManagerDynamicMappingIT.java

@@ -125,7 +125,7 @@ private void setupAndInspectIndex(String dynamicMapping) {
 				.withIndex( index );
 
 		if ( dynamicMapping != null ) {
-			setupContext.withIndexProperty( index.name(), ElasticsearchIndexSettings.DYNAMIC_MAPPING, dynamicMapping );
+			setupContext.withIndexProperty( index.name(), "dynamic_mapping", dynamicMapping );
 		}
 
 		setupContext.setup();