Suppress arm64 WebNN failures

Suppresses two recently added WebNN tests on Windows arm64 devices
since they are failing due to a known issue.

Bug: 41495927
Change-Id: I35f4c65058f06a9c350638ea00d488b8fbdbbd9f
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5411223
Commit-Queue: Brian Sheedy <bsheedy@chromium.org>
Commit-Queue: Rubber Stamper <rubber-stamper@appspot.gserviceaccount.com>
Bot-Commit: Rubber Stamper <rubber-stamper@appspot.gserviceaccount.com>
Auto-Submit: Brian Sheedy <bsheedy@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1280925}