Revert of Add accessibility_unittests and chromevox_tests to buildbot config.

Revert of Add accessibility_unittests and chromevox_tests to buildbot config. (https://codereview.chromium.org/350123003/)

Reason for revert:
The chromevox tests are failing (and blocking cq trybots).

Original issue's description:
> Add accessibility_unittests and chromevox_tests to buildbot config.
> 
> accessibility_unittests should run everywhere except iOS. It's small and
> very fast.
> 
> chromevox_tests is only for Chromium OS.
> 
> BUG=322537
> NOTRY=true
> 
> Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=280566

TBR=phajdan.jr@chromium.org,plundblad@chromium.org,dmazzoni@chromium.org
NOTREECHECKS=true
NOTRY=true
BUG=322537
Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=280590

[Timothy Loh, 2014-06-30 12:52:43]

Created Revert of Add accessibility_unittests and chromevox_tests to buildbot
config.

[commit-bot: I haz the power, 2014-06-30 12:53:09]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/timloh@chromium.org/338843007/1

[commit-bot: I haz the power, 2014-06-30 12:54:24]

Change committed as 280590

[Paweł Hajdan Jr., 2014-07-28 11:45:09]

LGTM