cq: enable more LUCI try builders

Bump experimental percentage of linux_chromium_rel_ng on LUCI to 5%
Enable {win,mac}_chromium_rel_ng builders

R=estaab@chromium.org, dpranke@chromium.org
BUG=
NOPRESUBMIT=true
NOTRY=true

Review-Url: https://codereview.chromium.org/2809313002
Cr-Commit-Position: refs/heads/master@{#463832}
1 file changed