Disable SendsAndReceivesVP9 test for now.

Fails on linux memcheck and DrMemory.
Will re-enable on next libvpx roll.

TBR=stefan@webrtc.org

Review URL: https://webrtc-codereview.appspot.com/27699004

git-svn-id: http://webrtc.googlecode.com/svn/trunk@7424 4adac7df-926f-26a2-2b94-8c16560cd09d