cmd/go: convert TestRunPkg to the script framework

Part of the effort to convert all non-parallel cmd/go tests to the script
framework.

Updates #17751
Updates #36320

Change-Id: I2bc0b1e5c03e2c49b5c79ac24a908a202840d5d4
Reviewed-on: https://go-review.googlesource.com/c/go/+/212879
Run-TryBot: Michael Matloob <matloob@golang.org>
Reviewed-by: Jay Conrod <jayconrod@google.com>

src/cmd/go/go_test.go

@@ -1026,18 +1026,6 @@ func TestInternalPackagesOutsideGOROOTAreRespected(t *testing.T) {
 	tg.grepBoth(`testinternal2(\/|\\)p\.go\:3\:8\: use of internal package .*internal/w not allowed`, "wrote error message for testdata/testinternal2")
 }
 
-func TestRunPkg(t *testing.T) {
-	tg := testgo(t)
-	defer tg.cleanup()
-	dir := filepath.Join(tg.pwd(), "testdata")
-	tg.setenv("GOPATH", dir)
-	tg.run("run", "hello")
-	tg.grepStderr("hello, world", "did not find hello, world")
-	tg.cd(filepath.Join(dir, "src/hello"))
-	tg.run("run", ".")
-	tg.grepStderr("hello, world", "did not find hello, world")
-}
-
 func TestInternalPackageErrorsAreHandled(t *testing.T) {
 	tg := testgo(t)
 	defer tg.cleanup()

src/cmd/go/testdata/script/run_hello_pkg.txt

+cd $GOPATH
+go run hello
+stderr 'hello, world'
+
+cd src/hello
+go run .
+stderr 'hello, world'
+
+-- hello/hello.go --
+package main
+
+func main() {
+	println("hello, world")
+}