Remove some unused options and make server_threads relevant
Start stubbing out better qps/core calculations

reset option to the mark, create a closed loop config params (empty
message) for consistency with other tests.

one for control.
Eliminate the use of our own SimpleRequest and SimpleResponse and
instead share the one from end2end testing

This change contains a lot of ugly changes, such as changing
std::vector to allocation by new, etc.

showing up as memory leaks

Also reduce the rate of the openloop test - this may be an issue with
sanitizers particularly because of issue #2278

Also fix reporter

maintain affinity of next_channel whenever possible