main.star: add builders with the c3h88 suffix for highcpu perf tests

This change adds linux-amd64_c3h88-perf* builders (c3h88 is an
abbreviation for c3-highcpu-88, the GCE instance type) for running
ad-hoc many-core performance tests.

Change-Id: If760771128751d5fd03230d7785aaa1ba914f62d
Reviewed-on: https://go-review.googlesource.com/c/build/+/580839
Reviewed-by: Dmitri Shuralyov <dmitshur@golang.org>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Dmitri Shuralyov <dmitshur@google.com>
3 files changed