[testing] Skip isolate/detect_nullsafety_2_test on Windows
[testing] Skip isolate/detect_nullsafety_2_test on Windows

https://github.com/dart-lang/sdk/issues/43583

Change-Id: I4d25013f2c92904854085349423254979687837b
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/165162
Reviewed-by: William Hesse <a821cddceae7dc400f272e3cb1a72f400f9fed6d@google.com>

dart-lang/sdk,dart-lang/sdk,dart-lang/sdk,dart-lang/sdk,dart-lang/sdk,dart-lang/sdk,dart-lang/sdk,dart-lang/sdk