Improve ASP code: config.py

- both add_additional_packages() and remove_additional_packages() are only ever called with search_new_persistence=True, so why is this argument even needed?
- as a result of the above, get_additional_packages() and _write_config are also only called with search_new_persistence=True

Parent Task: #14568 (closed)

Related issues

Related to #15838 (closed)

Original created by @u on 16062 (Redmine)

To upload designs, you'll need to enable LFS and have an admin enable hashed storage. More information