cmd/go: delete TestGetFileURL temporary file

Change-Id: I191ac2a2b469c6179d22d66c15f2d96ecb3d0902
Reviewed-on: https://go-review.googlesource.com/c/go/+/209970Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

src/cmd/go/internal/web/file_test.go

@@ -19,6 +19,8 @@ func TestGetFileURL(t *testing.T) {
 	if err != nil {
 		t.Fatal(err)
 	}
+	defer os.Remove(f.Name())
+
 	if _, err := f.WriteString(content); err != nil {
 		t.Error(err)
 	}