[gardening] Restrict timeout status to MacOS.
[gardening] Restrict timeout status to MacOS.

This modifies recent commit 25262fe9.

Change-Id: I19f8bc5bcefacbf761479869f79140702c37305b
Reviewed-on: https://dart-review.googlesource.com/c/85464
Auto-Submit: Régis Crelier <c2bf536a10d9f2530c38e4e8da517718be8c39ce@google.com>
Commit-Queue: Siva Annamalai <2e618a8cbd7bb6b3d4409061ae407d692a098546@google.com>
Reviewed-by: Siva Annamalai <2e618a8cbd7bb6b3d4409061ae407d692a098546@google.com>

dartino/dart-sdk,dart-archive/dart-sdk,dart-archive/dart-sdk,dart-lang/sdk,dart-archive/dart-sdk,dart-archive/dart-sdk,dart-lang/sdk,dartino/dart-sdk,dart-archive/dart-sdk,dart-lang/sdk,dart-archive/dart-sdk,dartino/dart-sdk,dart-archive/dart-sdk,dartino/dart-sdk,dartino/dart-sdk,dartino/dart-sdk,dart-lang/sdk,dart-lang/sdk,dartino/dart-sdk,dart-lang/sdk,dart-archive/dart-sdk,dartino/dart-sdk,dartino/dart-sdk,dart-lang/sdk,dart-archive/dart-sdk,dart-lang/sdk