cmd/internal/archive: don't rely on an erroneous install target in tests

cmd/internal/archive: don't rely on an erroneous install target in tests

Non-main packages in module mode should not be installed to
GOPATH/pkg, but due to #37015 they were installed there anyway.
This change switches the 'go install' command to instead use
'go build -buildmode=archive' with an explicit archive path.

For #37015.

Change-Id: Ib0c8f213100b6473a7657af96f31395703e28493
Reviewed-on: https://go-review.googlesource.com/c/go/+/414055
Auto-Submit: Bryan Mills <bcmills@google.com>
Reviewed-by: Cherry Mui <cherryyz@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Michael Matloob <matloob@golang.org>
Run-TryBot: Bryan Mills <bcmills@google.com>