benchmarks: Split BenchmarkRunner into many small methods
benchmarks: Split BenchmarkRunner into many small methods

We want to import BenchmarkRunner and overwrite a few of the
methods to re-use the Runner, client & server for Hyperbahn
benchmarks.

We would overwrite supportServices and relayServer to spawn
a Hyperbahn worker instead.

savaki/tchannel,savaki/tchannel,savaki/tchannel