max-transfer-time-* and max-transfer-idle-* broken since 9.15.6

In 53f0b6c3 ("convert ns_client and related objects to use netmgr"), the logic for setting a timer to enforce max-transfer-time-out and max-transfer-idle-out was removed.

In 49d53a4a ("use netmgr for xfrin"), the max-transfer-time-in and max-transfer-idle-in options have met a similar destiny.