sheriff: Disable ZipTest.BigFile on CrOS due to flakiness

Bug: 1300448
Change-Id: I0780ceb9150f1c59cb7b801f57431b8ead6cfe7a
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3489577


Owners-Override: Yuki Shiino <yukishiino@chromium.org>
Reviewed-by: Kentaro Hara <haraken@chromium.org>
Commit-Queue: Yuki Shiino <yukishiino@chromium.org>
Cr-Commit-Position: refs/heads/main@{#975040}
NOKEYCHECK=True
GitOrigin-RevId: 76d608ed096266c426e0a93ca5b8a85ab77aad72