Stop running nanobench on Test.*Debug bots

We'll need to add Perf.*Debug bots to achieve the same coverage.

BUG=skia:4768
GOLD_TRYBOT_URL= https://gold.skia.org/search?issue=2189393002
NOTREECHECKS=true

Review-Url: https://codereview.chromium.org/2189393002
27 files changed