Disable FullStackTest.ScreenshareSlidesVP9_2SL on all platforms
Disable FullStackTest.ScreenshareSlidesVP9_2SL on all platforms

The test is failing due to libvpx roll which will be fixed in future roll.
It wasn't discovered at trybots since webrtc_perf_tests doesn't run
on Mac because of webrtc:7322.

BUG=webrtc:7401
TBR=marpan@webrtc.org

Review-Url: https://codereview.webrtc.org/2774973002 .
Cr-Commit-Position: 972c6d2dc6dd5efdad1377c0d224e03eb8f276f7@{#17377}

ShiftMediaProject/libilbc,TimothyGu/libilbc,ShiftMediaProject/libilbc,TimothyGu/libilbc,ShiftMediaProject/libilbc,ShiftMediaProject/libilbc,TimothyGu/libilbc,TimothyGu/libilbc,TimothyGu/libilbc,ShiftMediaProject/libilbc