runtime: use maxprocs instead of stwprocs for GC CPU pause time metrics
Currently we use stwprocs as the multiplier for the STW CPU time
computation, but this isn't the same as GOMAXPROCS, which is used for
the total time in the CPU metrics. The two numbers need to be
comparable, so this change switches to using maxprocs to make it so.
Change-Id: I423e3c441d05b1bd656353368cb323289661e302
Reviewed-on: https://go-review.googlesource.com/c/go/+/570256
Auto-Submit: Michael Knyszek <mknyszek@google.com> Reviewed-by: Nicolas Hillegeer <aktau@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>