[System] Add some debugging code to BeginConnectMultiple test.

The WaitOne () call has a tendency to time out on the Jenkins
VMs. However, reproducing the problem outside of Jenkins has
proven futile.

This makes the WaitOne () call block for as long as needed and
still fails the test if the elapsed time was longer than 30s.
We print the actual elapsed time to the console.

Hopefully this'll help us find out if it's just taking quite a
long time to run or if it's a hang.