Revert the commit which breaks ci-license-scan
Revert "Copyright.add_files_paragraph(): Append after the last existing files paragraph."
This partially reverts commit e7990d2ab83057a2aaf7851f4250f1072f6fee8c.
When license scanner returns UNKNOWN, it uses Files: * paragraph of debian/copyright and use it as the default license. This works in bullseye python-debian version 0.1.39 and in bookworm version 0.1.49, it still reports UNKNOWN. The issue is causes by commit e7990d2a, so revert it for the license scanner to report correct licenses.