The goal of this change is improve the stability of the stress test avoiding unexpected timeouts. This change also provide a way to configure the stress-test to run for a defined time period, it's particular interesting for when it's running in test-kit in cluster mode simulating the change on the cluster composition.

…ers (#669) (#670)

The lack of set channel._open to false when the onclose event is triggered was causing the channel be broken without the other parts of the driver notice. In tbis way, a next iteration trying to get the broken connection will succeded in the try and run the query will result in a eternal pending promise.

Mark the channel as closed enable the pool to discard and create a new connection if it needed.