BUG/MAJOR: dns: tcp session can remain attached to a list after a free

BUG/MAJOR: dns: tcp session can remain attached to a list after a free

Using tcp, after a session release and free, the session can remain
attached to the list of sessions with a response message waiting for
a commit (ds->waiter). This results to a use after free of this
session.

Also, on some error path and after free, a session could remain attached
to the lists of available idle/free sessions (ds->list).

This patch ensure to remove the session from those external lists
before a free.

This patch should be backported to all version including
the dns over tcp (2.4)