resolved: register ipv4only.arpa are private domain

resolved: register ipv4only.arpa are private domain

From RFC 8880:

Because the 'ipv4only.arpa' zone has to be an insecure delegation,
DNSSEC cannot be used to protect these answers from tampering by
malicious devices on the path.

Consequently, the 'ipv4only.arpa' zone MUST be an insecure delegation to
give DNS64/NAT64 gateways the freedom to synthesize answers to those
queries at will, without the answers being rejected by DNSSEC-capable
resolvers. DNSSEC-capable resolvers that follow this specification MUST
NOT attempt to validate answers received in response to queries for the
IPv6 AAAA address records for 'ipv4only.arpa'. Note that the name
'ipv4only.arpa' has no use outside of being used for this special DNS
pseudo-query used to learn the DNS64/NAT64 address synthesis prefix, so
the lack of DNSSEC security for that name is not a problem.

See: https://datatracker.ietf.org/doc/html/rfc8880#name-security-considerations