GN: take over some exisiting bots

As an experiment, instead of replacing these with -GN twins, take
them over in-place.  This should take over:

  -FAST
  -SKFOO

CQ_INCLUDE_TRYBOTS=master.client.skia:Perf-Ubuntu-GCC-GCE-CPU-AVX2-x86_64-Debug-SK_USE_DISCARDABLE_SCALEDIMAGECACHE-Trybot,Test-Ubuntu-GCC-GCE-CPU-AVX2-x86_64-Debug-SK_USE_DISCARDABLE_SCALEDIMAGECACHE-Trybot,Test-Ubuntu-GCC-GCE-CPU-AVX2-x86_64-Release-SKNX_NO_SIMD-Trybot,Test-Ubuntu-GCC-GCE-CPU-AVX2-x86_64-Release-Fast-Trybot

BUG=skia:
GOLD_TRYBOT_URL= https://gold.skia.org/search?issue=2229463002

Review-Url: https://codereview.chromium.org/2229463002
7 files changed