[debian] Update debian packaging (closes #16133259)
- use dh_python, pybuild and debhelper>=9,
- refactor and simplify the debian/rules,
- rename binary packages (but cubicweb-ctl) to python-xxx
- remove daemon handling stuff (initscripts...) from cubicweb-ctl (one should
now use a standard WSGI delivery method),
cubicweb source: source-is-missing cubicweb/web/data/jquery.flot.js line length is * characters (>512)