testing: remove stale builder names from windows tests
A couple of the windows runtime tests were being gated by "if
testenv.Builder() == ..." guards that referred to builders that have
long since been obsoleted (e.g. "windows-amd64-gce"). Use a more
generic guard instead, checking for windows-<goarch> prefix.
Change-Id: Ibdb9ce2b0cfe10bba986bd210a5b8ce5c1b1d675
Reviewed-on: https://go-review.googlesource.com/c/go/+/453035 Reviewed-by: Dmitri Shuralyov <dmitshur@google.com> Reviewed-by: Dmitri Shuralyov <dmitshur@golang.org>
Run-TryBot: Than McIntosh <thanm@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>