After migration of catalog to ERP5-ified document, its better to migrate all the catalog methods (`ZSQL Method, Python Script`) to new format. This will save the 
time during migration for developers and will reduce the chance for error during *import_in_old_format >> export_in_new_format* process.


Some important changes during re-export:
- Classes for new catalog methods are now defined via `portal_type`
- Filter is now defined via properties, so no need to save their properties in `.catalog_keys.xml` file.

/reviewed-on nexedi/erp5!518

erp5_pdm: use preferred category child item list method in my_variation_category_list field library.

Python script needs to be recompiled when they comes from a change of
class. This was done when business template was installing scripts, but
not when automatic migration from old catalog to new catalog was done.
So make sure to call _compile directly in changeObjectClass to make sure
Python Scripts would always work after a change of class.