[debian] Remove unused/redundant entries from debian/cubicweb-ctl.dirs * bash completion entry produces a lintian warning "package-installs-into-obsolete-dir etc/bash_completion.d/", and it does not install bash completion. * doc directory should be handled automatically.

docutils
Twisted < 16.0.0
requests
webtest
cubicweb-blog
cubicweb-file >= 2.0.0
cubicweb-tag