Disable CircleCI builds for now

After discussion with @harterrt, I now understand that
reports-dev.telemetry.mozilla.org is currently populated from
mozilla-services/mozilla-private-reports and we need to preserve that
for now.

So, we'll turn off deploys for this repo for now and I'll be writing
up a bug to track the steps necessary to make this repo private,
copy over the mozilla-private-reports content, and eventually
retire the existing Knowledge Repo.