[Bug] Random error during start

[shargon]

Describe the bug

In my opinion, the issue that #4244 tried to fix wasn’t actually resolved — it was just hidden. As @Jim8y mentioned:

• Peer.OnTcpConnected always assumed both the Akka Tcp.Connected envelope and
  the actor’s Config field were ready. In practice that’s not guaranteed:
• Akka can deliver a Tcp.Connected message whose RemoteAddress is null when
  the socket aborts during the OS handshake. The old code immediately cast
  that to IPEndPoint and called .UnMap(), so the very first dereference blew
  up with a NullReferenceException.
• There’s also a race between wiring up ChannelsConfig (handled in OnStart)
  and the inflight connect that triggers Tcp.Connected. When the connect
  arrived before OnStart ran, Config was still null, and the subsequent
  Config.MaxConnections… lookup faulted.

We should try to find the root cause of the problem instead of hiding it.

[Wi1l-B0t]

Yes, this requires more investigation.

There might be a better way to fix it, but for now, the current approach is acceptable.