Refactors the perf tests to fix the issue of metric and story being
swapped, which causes issues when trying to convert to histograms.

Specifically, does the following:
1. Rolls the version of src/tests/perf_tests/third_party/perf/ to
   Chromium 476dae823269c8d05b544271af97ad1adb0db8ee
2. Switch to using PerfResultReporter instead of PrintResult directly.
3. Split RenderTestParams::suffix into backend and story; backend is
   used as part of the metric, while story is used as the story.
4. Remove the "average" metric that was being automatically reported
   by ANGLEPerfTest, as reported results are automatically averaged.
5. Update the reported metric to more clearly distinguish between
   test, backend, and metric. It is now name_backend.metric. e.g.
   DrawCallPerf_vulkan.wall_time.

Bug: chromium:923564,chromium:924618
Change-Id: I00cc191407052f23df57dbfa53b6fb088fc26960
Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/1762360
Commit-Queue: Jamie Madill <jmadill@chromium.org>
Reviewed-by: Jamie Madill <jmadill@chromium.org>
Reviewed-by: Jonah Ryan-Davis <jonahr@google.com>