[release-branch.go1.13] cmd/go: fix and skip known Windows test failures

These non-short Windows test failures were resolved fully in CL 206144.

Both TestScript/build_trimpath and TestScript/version tests can be fixed
by backporting the changes to test scripts only, so that is done here.

Fixing TestScript/mod_list_dir requires backporting non-test changes in
addition to the test script changes, which is unlikely to be appropriate
this late in Go 1.13 release cycle. A failing test can cover up other
regressions, so skip this known failing test to fix the builder.

For #36181.

Change-Id: I4f140bd373554eb4664f04638666dee77986ec3e
Reviewed-on: https://go-review.googlesource.com/c/go/+/223782


Run-TryBot: Dmitri Shuralyov <dmitshur@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Jay Conrod <jayconrod@google.com>