[Bug]: Sorter for groups in classificationstore is still not considered

### Expected behavior

Groups are sorted via sorter

### Actual behavior

Groups are sorted via internal id

### Steps to reproduce

1. Go to demo.pimcore.fun
2. Create ClassificationStore, add groups and keys with sorters
3. Add Group to an object
4. Groups is sorted via sorter
5. Save and reload object
6. Groups are sorted via internal id