1. Remove all deadlines from the RPCs and shutdown in this code.

   These tests (especially unconstrained versions) can get very
   backlogged and may take a while to finish. We sometimes flake waiting
   for that. This is not hazardous (IMO), as the scripts that run these
   tests already have timeouts to make sure that these don't truly go on
   forever.

2. Make the time spent in the benchmark phase actually be
   benchmark_seconds rather than benchmark_seconds-warmup_seconds
   as it is currently.