cmd/go: roll forward "convert TestShadowingLogic to the script framework"

cmd/go: roll forward "convert TestShadowingLogic to the script framework"

This rolls forward the change golang.org/cl/214431, which was reverted
in golang.org/cl/220217. The cl was broken because
TestVersionControlErrorMessageIncludesCorrectDirectory, which is going
to be removed in golang.org/cl/214429 hadn't been submitted yet.

Original change description:

Part of converting all tests to script framework to improve
test parallelism.

Updates #36320
Updates #17751

Change-Id: I87b3f9acb8575fbcbd58d454b5f9bac4923429b3
Reviewed-on: https://go-review.googlesource.com/c/go/+/220178
Run-TryBot: Michael Matloob <matloob@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Bryan C. Mills <bcmills@google.com>