Revert "Sheriff: Disable graphics.VAAPIUnittest"

This reverts commit 846b0684.

Reason for revert: a CL has been landed fixing the issue
that broke the two tests that this CL is disabling, so we
shouldn't need this workaround.

See https:/crbug.com/1105335.

Original change's description:
> Sheriff: Disable graphics.VAAPIUnittest
> 
> TBR=andrescj@chromium.org
> TBR=gildekel@chromium.org
> 
> Bug: 1105335
> Change-Id: Ibf8e4794604bf0eaf32fc50f3e11d9f3f40468cf
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2296607
> Reviewed-by: Fergus Dall <sidereal@google.com>
> Commit-Queue: Fergus Dall <sidereal@google.com>
> Cr-Commit-Position: refs/heads/master@{#788071}

TBR=andrescj@chromium.org,sidereal@google.com,gildekel@chromium.org

# Not skipping CQ checks because original CL landed > 1 day ago.

Bug: 1105335
Change-Id: I352e77dc659d478e77297cddc4e67c4b7c388b8d
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2299188Reviewed-by: Miguel Casas <mcasas@chromium.org>
Commit-Queue: Miguel Casas <mcasas@chromium.org>
Cr-Commit-Position: refs/heads/master@{#788685}

chromeos/BUILD.gn

@@ -310,10 +310,6 @@ if (is_chromeos_device) {
 
       # crbug.com/1099695
       "platform.Drivefs",
-
-      # crbug.com/1105335
-      "graphics.VAAPIUnittest.jpeg_decoder",
-      "graphics.VAAPIUnittest.common",
     ]
   }