In the CQ, prioritize changes that were verified by Pre-CQ.
In the CQ, prioritize changes that were verified by Pre-CQ.

This ensures that changes that are verified by Pre-CQ don't get kicked
out by changes that weren't verified by Pre-CQ.

If we only see changes that weren't verified by Pre-CQ, try all of the
changes. This ensures that the CQ continues to work even if the Pre-CQ is
down.

BUG=chromium:229101, chromium:233081
TEST=mario-paladin run, unit tests. Verify changes that weren't verified
     get kicked out, and changes that were verified stay in.

Change-Id: I075c7bcba50d4c9a4203dc1ada47d95bc5d7fc2d
Reviewed-on: https://gerrit.chromium.org/gerrit/49644
Tested-by: David James <f231dc574bbeb62604660cbc162d1b8642a0a3af@chromium.org>
Reviewed-by: Ryan Cui <5ce1592d53754a87a44fc2eb7b63d5f77cf50fdb@chromium.org>
Commit-Queue: David James <f231dc574bbeb62604660cbc162d1b8642a0a3af@chromium.org>
Reviewed-by: Chris Sosa <959d3d631fb6f17f1b07f751372041a1edb210d1@chromium.org>

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