ooni probe is not generic

The ooni probe tests are riseup specific at the (its checking black.riseup.net reachability) moment, although the plan for the future is to make them more generic, so any provider can benefit from them.

However, right now if any provider deploys lilypad, they'll get contacted by ooni.org because of high traffic to their API related to the 'riseupvpn' OONI experiment. This is because every 6 hours, the ooni-exporter runs which queries api.ooni.io and this runs for ~1hr.

It makes sense to keep this service around, for when the probes can be made generic, but until then it should be only optionally enabled, instead of enabled by default.