Don't record connect/disconnect events for short-lived connections with no valid messages received

[kwbc]

Currently connect & disconnect events are recorded for all connections to the external port, regardless of whether any data is received on a connection. This can produce a lot of junk in the archive if a load-balancer is repeatedly opening and closing connections to detect if the port is open, or some random party on the internet is repeatedly connecting for whatever reason. Also, these events lack timestamps.

I propose the following changes:

1. Add timestamps to the Connect & Disconnect events.
2. Don't record the connect (or disconnect) event until at least one valid FIX message is received.
3. Increment a new counter for connections that disconnect without having received any valid messages.

With the counter you still have some indication that short-lived connections with no messages are occurring, and can use Wireshark or the like to investigate further if need be.

[RichardWarburton]

I don't think there's any objection to this that I've seen. I'd happily accept that as a change.