cmd/go: convert some more tests to script tests

cmd/go: convert some more tests to script tests

Convert more tests to script tests so they can run in parallel with the
rest of the script tests. This CL converts
TestPackageMainTestCompilerFlags, TestGoListTest,
TestListTemplateContextFunction, and TestIssue22588.

Change-Id: I4f8410e85d4811e82d85d884d28a2a0d6a6a6964
Reviewed-on: https://go-review.googlesource.com/c/go/+/727420
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Michael Matloob <matloob@google.com>
Reviewed-by: Alan Donovan <adonovan@google.com>