Fix cbuildbot_config_unittest.py.
Fix cbuildbot_config_unittest.py.

Right now, daisy does not work on public boards so we cannot enable it
on chromium.chromiumos. So I've added a workaround to keep the test
passing.

BUG=none
TEST=Run cbuildbot_config_unittest, verify it passes.

Change-Id: If1097e54f07e6ddd2566b81421d8e31ddcfeab28
Reviewed-on: https://gerrit.chromium.org/gerrit/22518
Reviewed-by: Brian Harring <fdc2d0a2e2340b623587cee5ea8dff425d1eb1f3@chromium.org>
Tested-by: David James <f231dc574bbeb62604660cbc162d1b8642a0a3af@chromium.org>
Commit-Ready: David James <f231dc574bbeb62604660cbc162d1b8642a0a3af@chromium.org>

coreos/chromite,zhang0137/chromite,coreos/chromite,zhang0137/chromite,zhang0137/chromite,coreos/chromite,bpsinc-native/src_third_party_chromite,bpsinc-native/src_third_party_chromite,chadversary/chromiumos.chromite,bpsinc-native/src_third_party_chromite,chadversary/chromiumos.chromite