Disable flaky memory_mobile/browse:news:cnn:2021.

Bug: 1428625
Change-Id: I6ca001cd9da5d923286a62573322fc160876b16e
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/4376071


Commit-Queue: Sky Malice <skym@chromium.org>
Reviewed-by: Brandon Wylie <wylieb@chromium.org>
Auto-Submit: Sky Malice <skym@chromium.org>
Owners-Override: Sky Malice <skym@chromium.org>
Commit-Queue: Brandon Wylie <wylieb@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1123186}