BroadcastNetworkFailure called twice when outdated client network failure is received

When a pending net game on a client receives a NMT_Upgrade control message, a network failure of type OutdatedClient is broadcast. Then during TickWorldTravel when the client tries to return to the default map, BroadcastNetworkFailure is called again with the same error. It appears as though UOnlineSessionClient::HandleDisconnect calls UOnlineSessionClient::HandleDisconnectInternal, skipping over UEngine::HandleDisconnect, so the session is destroyed but the pending net game is not shutdown until after the second failure is broadcast.

Connect a client with an older version of a game to a server running a newer version.

Expected: BroadcastNetworkFailure will be called once with an error type of OutdatedClient.

Actual: BroadcastNetworkFailure is called twice.