[Telemetry] Disable memory.top_7_stress.

[Telemetry] Disable memory.top_7_stress.

It has been failing on most bots since it was enabled in 309340. Example:
http://build.chromium.org/p/chromium.perf/builders/Linux%20Perf%20%283%29/builds/7078/steps/memory.top_7_stress/logs/stdio

TBR=hashimoto@chromium.org
BUG=

Committed: https://crrev.com/b7ff901b74b7a5cfa820e4b7fa5a25ef31a3e398
Cr-Commit-Position: refs/heads/master@{#309379}

[tonyg, 2014-12-21 19:32:34]

The CQ bit was checked by tonyg@chromium.org

[commit-bot: I haz the power, 2014-12-21 19:32:56]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/810333004/1

[commit-bot: I haz the power, 2014-12-21 21:17:34]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2014-12-21 21:18:29]

Patchset 1 (id:??) landed as
https://crrev.com/b7ff901b74b7a5cfa820e4b7fa5a25ef31a3e398
Cr-Commit-Position: refs/heads/master@{#309379}

[hashimoto, 2014-12-22 15:36:57]

On 2014/12/21 21:18:29, I haz the power (commit-bot) wrote:
> Patchset 1 (id:??) landed as
> https://crrev.com/b7ff901b74b7a5cfa820e4b7fa5a25ef31a3e398
> Cr-Commit-Position: refs/heads/master@{#309379}

Sorry for the mess, and thank for taking care of this.