community/knot-resolver: do not depend on dns-root-hints
Instead rely on the root hints provided by knot-resolver itself.
See #11324 (closed) for the reasoning behind this.
We are currently working on getting Alpine Linux 3.21 out. This means that merge requests that are not aimed to help with that (only affecting testing, new aports) have a lower priority at the moment. Please be patient, they will be eventually picked up.
Instead rely on the root hints provided by knot-resolver itself.
See #11324 (closed) for the reasoning behind this.