TransportAbortHandlerIsMovingOn - removing transport abort handler

(We wish him luck in /dev/null)

Fixes workitems #3067 and #3102
I just noticed that unlike the other .NET transports, this one does not stop the connection when only the `disconnectToken` passed into `Start` is tripped. This can be important, because there are situations (such as a reconnect timeout) where `Disconnect` will be called but not `Stop` meaning that `AbortSent` will remain false.

`Disconnect` does dispose the transport, so that might mitigate this issue, but I think it is still worth looking into.