Disable flaky AppContextMenuTest.ArcMenuSuspendedItem.

This test occasionally triggers a fatal failure in
DataDecoder::GetService().

Bug: 1115762
Change-Id: I12a46b8ac2f9e3805269e3c4fef3985e0e961147
Tbr: khmel@chromium.org
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2357617


Reviewed-by: Lei Zhang <thestig@chromium.org>
Commit-Queue: Lei Zhang <thestig@chromium.org>
Cr-Commit-Position: refs/heads/master@{#798342}