Resolve "MtTcpListenerMgr::stop() destroys listener without stopping it first"

Closes #2655 (closed)

MtTcpListenerMgr::stop() doesn't stop the the listener instance before destroying it. This can leave the socket still in use at the OS level. I found this while testing in-progress class, MtLeaseQueryListenerMgr, one UT would pass, a subsequent tests would fail with listener failing to start due to address already in-use. The HTTP class hierarchy from which these were modeled does stop it, so this got dropped.