testing: use QueryPerformanceCounter on Windows

testing: use QueryPerformanceCounter on Windows

Windows time.Now granularity is around 0.5ms on modern systems,
which introduces a significant noise into benchmark results.
Instead of relying time.Now use QueryPerformanceCounter, which
has significantly better granularity compared to time.Now.

 │ TimeNow-32  │        HighPrecisionTimeNow-32        │
 │   sec/op    │    sec/op     vs base                 │
   4.812n ± 0%   30.580n ± 0%  +535.43% (p=0.000 n=20)

Fixes #31160

Change-Id: Ib2a574d638c9c6762a2524212def02265574e267
Reviewed-on: https://go-review.googlesource.com/c/go/+/557315
Reviewed-by: Quim Muntal <quimmuntal@gmail.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Alex Brainman <alex.brainman@gmail.com>
Reviewed-by: Cherry Mui <cherryyz@google.com>
Reviewed-by: Michael Knyszek <mknyszek@google.com>