Revert of Run Mojo apptests step on Windows main and cq bots.

Revert of Run Mojo apptests step on Windows main and cq bots. (patchset #2 id:20001 of https://codereview.chromium.org/1412563007/ )

Reason for revert:
The mojo_apptests step is failing flakily due to a high incidence rate of http://crbug.com/551083 (Flaky mojo BaseThreadInitThunk / RtlInitializeExceptionChain crashes on Windows)

Original issue's description:
> Run Mojo apptests step on Windows main and cq bots.
>
> Add mojo_apptests step to 'Win8 Aura' buildbot config for these bots:
>   http://build.chromium.org/p/chromium.win/builders/Win8%20Aura
>   http://build.chromium.org/p/tryserver.chromium.win/builders/win8_chromium_ng
>
> The step has run on FYI for months, with no flakes for 1 week:
>   http://build.chromium.org/p/chromium.mojo/builders/Chromium%20Mojo%20Windows
> (recent changes addressed blocking flakiness: http://crbug.com/517661)
>
> BUG=478244, 517661
> TEST=New step passes on intended bots.
> R=dpranke@chromium.org
> TBR=phajdan.jr@chromium.org
>
> Committed: https://crrev.com/3e18cf082b743ba0209a38509f2b62f0c9b76638
> Cr-Commit-Position: refs/heads/master@{#357425}

TBR=phajdan.jr@chromium.org,dpranke@chromium.org
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=478244, 517661
Committed: https://crrev.com/e3faad772792c9be1254bcc72aa4ce05ac810415
Cr-Commit-Position: refs/heads/master@{#358105}

[msw, 2015-11-05 19:20:15]

Created Revert of Run Mojo apptests step on Windows main and cq bots.

[commit-bot: I haz the power, 2015-11-05 19:21:12]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1413773009/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1413773009/1

[commit-bot: I haz the power, 2015-11-05 19:22:23]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-11-05 19:23:12]

Patchset 1 (id:??) landed as
https://crrev.com/e3faad772792c9be1254bcc72aa4ce05ac810415
Cr-Commit-Position: refs/heads/master@{#358105}