cmd/go: convert some vet tests to the script framework

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

Updates #36320
Updates #17751

Change-Id: I1f49a84f91735f39d5922c1347e79298780149c7
Reviewed-on: https://go-review.googlesource.com/c/go/+/214218


Reviewed-by: Jay Conrod <jayconrod@google.com>