cmd/go: skip broken TestScript/build_acl_windows on arm

Updates #30711

Change-Id: I280f7effaf488d5d9908d9d0cd1e0e99c22f91ca
Reviewed-on: https://go-review.googlesource.com/c/go/+/167778Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

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

 [!windows] stop
+[arm] skip # TODO(golang.org/issue/30711): Skip broken test.
 [!exec:icacls] skip
 [!exec:powershell] skip