VEA unittest: remove bitrate test on chromeos temporarily

Some bitrate tests always fail. Disable them temporariliy to prevent
they hide new regressions.

BUG=693336
CQ_INCLUDE_TRYBOTS=master.tryserver.chromium.android:android_optional_gpu_tests_rel;master.tryserver.chromium.linux:linux_optional_gpu_tests_rel;master.tryserver.chromium.mac:mac_optional_gpu_tests_rel;master.tryserver.chromium.win:win_optional_gpu_tests_rel

Review-Url: https://codereview.chromium.org/2764823003
Cr-Original-Commit-Position: refs/heads/master@{#458687}
Cr-Mirrored-From: https://chromium.googlesource.com/chromium/src
Cr-Mirrored-Commit: 2dd1b283c45c4bf5922de632a2b863d3339816db
1 file changed