Deletion of empty_scalars.csv after writing default scalars is missing

[MaGering]

After default_scalars.csv is created from empty_scalars.csv, empty_scalars.csv is not further needed and can be deleted for the sake of clarity.

This should be implemented in write_default_scalars module.

[nesnoj]

Please close or label with "wontfix" if not really essential for pipeline execution and results