runtime: use correct state machine in addAdjustedTimers

The addAdjustedTimers function was a late addition, and it got some of
the state machine wrong, leading to failures like
https://storage.googleapis.com/go-build-log/930576b6/windows-amd64-2016_53d0319e.log

Updates #6239
Updates #27707

Change-Id: I9e94e563b4698ff3035ce609055ca292b9cab3df
Reviewed-on: https://go-review.googlesource.com/c/go/+/204280


Run-TryBot: Ian Lance Taylor <iant@golang.org>
Reviewed-by: Michael Knyszek <mknyszek@google.com>