Disable EndToEnd.GetStats test.

Looks like this test exposes a bug in jitter buffer after enabling
multiple streams. Will disable to be able to debug it in peace and not
have to revert.

TBR=stefan@webrtc.org
BUG=4014

Review URL: https://webrtc-codereview.appspot.com/31009004

git-svn-id: http://webrtc.googlecode.com/svn/trunk@7704 4adac7df-926f-26a2-2b94-8c16560cd09d