[Sheriff] Disable flaky SSLUIWorkerFetchTest.MixedContent* tests on Win.

The tests cause a lot of flakes on Windows 7 dbg buildbot.

TBR=horo@chromium.org, jkrcal@chromium.org, adithyas@chromium.org

Bug: 443374
Change-Id: Id1145fcb274fc39b7672782ceb45224be0580daa
Reviewed-on: https://chromium-review.googlesource.com/595688
Reviewed-by: Jan Krcal <jkrcal@chromium.org>
Commit-Queue: Jan Krcal <jkrcal@chromium.org>
Cr-Commit-Position: refs/heads/master@{#490976}
1 file changed