cmd/go: convert TestBenchTimeout to the script framework

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

Updates #36320
Updates #17751

Change-Id: I5dc403726f4960482ed7c267d1a333bbcc260087
Reviewed-on: https://go-review.googlesource.com/c/go/+/213828
Reviewed-by: Jay Conrod <jayconrod@google.com>

src/cmd/go/go_test.go

@@ -3173,14 +3173,6 @@ const (
 	okPattern        = `(?m)^ok`
 )
 
-// Issue 18845
-func TestBenchTimeout(t *testing.T) {
-	tooSlow(t)
-	tg := testgo(t)
-	defer tg.cleanup()
-	tg.run("test", "-bench", ".", "-timeout", "750ms", "testdata/timeoutbench_test.go")
-}
-
 // Issue 19394
 func TestWriteProfilesOnTimeout(t *testing.T) {
 	tooSlow(t)

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

@@ -0,0 +1,18 @@
+# Tests issue #18845
+[short] skip
+
+go test -bench . -timeout=750ms timeoutbench_test.go
+stdout ok
+stdout PASS
+
+-- timeoutbench_test.go --
+package timeoutbench_test
+
+import (
+	"testing"
+	"time"
+)
+
+func BenchmarkSleep1s(b *testing.B) {
+	time.Sleep(1 * time.Second)
+}

src/cmd/go/testdata/timeoutbench_test.go

@@ -1,10 +0,0 @@
-package timeoutbench_test
-
-import (
-	"testing"
-	"time"
-)
-
-func BenchmarkSleep1s(b *testing.B) {
-	time.Sleep(1 * time.Second)
-}