Prepare group export feature to use ndjson

app/services/groups/import_export/export_service.rb

@@ -65,7 +65,7 @@ module Groups
       end
 
       def tree_exporter_class
-        if ::Feature.enabled?(:group_export_ndjson, @group&.parent)
+        if ::Feature.enabled?(:group_export_ndjson, @group&.parent, default_enabled: true)
           Gitlab::ImportExport::Group::TreeSaver
         else
           Gitlab::ImportExport::Group::LegacyTreeSaver

changelogs/unreleased/enable-group-export-ndjson-by-default.yml

+---
+title: Prepare group export feature to use ndjson
+merge_request: 31742
+author:
+type: changed