The go test result must not be cached when each of known variables to go
command change.

To do this, add all known variables to test metadata.

Fixes #32285

Change-Id: I90be6a72f46c42d965aec4fed534c0623244cd3d
Reviewed-on: https://go-review.googlesource.com/c/go/+/179040
Run-TryBot: Cuong Manh Le <cuong.manhle.vn@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Bryan C. Mills <bcmills@google.com>
Reviewed-by: Jay Conrod <jayconrod@google.com>