[gardener] Disable flaky test

Disable
LoginAuthUserViewPinOnlyPixeltest.PinOnlyModeWithAutosubmitEnabled.
It's flaky.

Bug: 361559383
Change-Id: If1da87a20d7c799d725abf072d5c9bc978a5d579
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5829088


Owners-Override: Nina Satragno <nsatragno@chromium.org>
Commit-Queue: Nina Satragno <nsatragno@chromium.org>
Commit-Queue: Frank Liberato <liberato@chromium.org>
Reviewed-by: Frank Liberato <liberato@chromium.org>
Auto-Submit: Nina Satragno <nsatragno@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1349384}