RestPerfClient: Invalid requests rate reported when a thread times out

If a synchronous request sending thread aborts due to a timeout, the RestPerfClient still assumes it managed to send all requests and generates invalid "requests per second" value which is calculated as "scheduled count of requests" / "timeout in seconds" (if there is 1 thread, I did not test the behavior in a situation when there is more than one thread). This problem can be seen in the attached output log file.