infra: Use logarithmic batching in LUCI config. This ensures we get more atomic testing and can more easily spot which CL regressed for perf tests or experimental bots. Bug: angleproject:7152 Change-Id: I402cf71be66c365ab509bd9e8d2a5f8c338ab1e3 Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/3563514 Auto-Submit: Jamie Madill <jmadill@chromium.org> Reviewed-by: Yuly Novikov <ynovikov@chromium.org> Commit-Queue: Yuly Novikov <ynovikov@chromium.org>