[server] remove some pre 3.10 compat Let's assume nobody will try upgrading an instance from pre-3.10 cubicweb to 3.23+. If they do, they're setting themselves up for a lot of pain anyway.

addressbook
basket
blog
book
calendar
comment
company
email
file
folder
i18ncontent
keyword
link
mailinglist
person
tag
timeseries
vcsfile