Fix TCPDNS and TLSDNS timers

After the TCPDNS refactoring the initial and idle timers were broken and only the tcp-initial-timeout was always applied on the whole TCP connection.

This broke any TCP connection that took longer than tcp-initial-timeout, most often this would affect large zone AXFRs.

This commit changes the timeout logic in this way:

• On TCP connection accept the tcp-initial-timeout is applied and the timer is started
• When we are processing and/or sending any DNS message the timer is stopped
• When we stop processing all DNS messages, the tcp-idle-timeout is applied and the timer is started again