Clean up unbound configs/zones on single test instances

[mxsasha]

Our single test instances* have unbound configs in two locations (/opt/internetnl/Internet.nl/_unbound/etc/unbound/, /opt/internetnl/unbound/etc/unbound/) with references between them, which has caused an incidental configuration issue, is sloppy, and may cause further issues.

We should clean this up. May be obsoleted if we integrate this into a docker setup.

*this may apply on batch as well, but we don't serve authoritative there