remove most 3.10 bw compat Related to #3799117. The boxes and entityvcomponent objects cannot really be removed as they are still used throughout the code base (and possible cubes). This may be caused by a non-working deprecation and needs some more work.

etc/init.d
etc/cubicweb.d
etc/bash_completion.d
usr/bin
usr/share/doc/cubicweb-ctl
var/log/cubicweb
var/lib/cubicweb/backup
var/lib/cubicweb/instances