Akka.IO: `TcpConnection` does not propagate closure events reliably

[Aaronontheweb]

Version Information
Version of Akka.NET? v1.5.41
Which Akka.NET Modules? Akka.IO

Describe the bug

Yet another Akka.IO bug - while working on #7633 I tried to tests to verify that we can track connection closures, but there's a small problem: the TcpConnection actor doesn't reliably transmit this information.

Expected behavior

If the remote socket gets closed, the local socket should close and report back to its handler immediately.

Actual behavior

Wildly different stuff depending on how the socket was closed. Sometimes an event, usually not.

Additional context

This code is wildly over-engineered and is in drastic need of cleanup.