Disable unittests on chrome perf bots.
Disable unittests on chrome perf bots.

They don't add value, and may stop working.

BUG=chromium:361801
TEST=config_unittest.py

Change-Id: I2e966d1b814beed20542cbb5580537c1b82924f5
Reviewed-on: https://chromium-review.googlesource.com/194133
Reviewed-by: David James <f231dc574bbeb62604660cbc162d1b8642a0a3af@chromium.org>
Commit-Queue: Peter Mayo <3d31fdaf44dc55bb1b4f50b19df9bc879177d37a@chromium.org>
Tested-by: Peter Mayo <3d31fdaf44dc55bb1b4f50b19df9bc879177d37a@chromium.org>

bpsinc-native/src_third_party_chromite,bpsinc-native/src_third_party_chromite,chadversary/chromiumos.chromite,chadversary/chromiumos.chromite,bpsinc-native/src_third_party_chromite