os/exec: disable failing LookPathTest on windows/arm64
os/exec: disable failing LookPathTest on windows/arm64

For #44379.

Change-Id: I9a3cf4d511a8286117f877c2ff9dbde56fa55983
Reviewed-on: https://go-review.googlesource.com/c/go/+/293709
Reviewed-by: Cherry Zhang <d62e63aa42ce272d7b6a5055d97e942b33a34679@google.com>
Trust: Russ Cox <5ad239cb8a44f659eaaee0aa1ea5b94947abe557@golang.org>

nawawi/go,nawawi/go,golang/go,CAFxX/go,cloudflare/go,CAFxX/go,nawawi/go,nawawi/go,nawawi/go,nawawi/go,golang/go,cloudflare/go,CAFxX/go,CAFxX/go,cloudflare/go,CAFxX/go,cloudflare/go,cloudflare/go,CAFxX/go,CAFxX/go,cloudflare/go,cloudflare/go,nawawi/go,golang/go,cloudflare/go,golang/go,golang/go,golang/go,golang/go,golang/go,nawawi/go,CAFxX/go