unbound needs to have cache-max-negative-ttl parameter for adjustment of the maximum TTL specifically for caching negative DNS responses

Issue

• unbound doesn't have cache-max-negative-ttl parameter, and the maximum TTL specifically for caching negative DNS responses can not be adjusted.
• Previously, this limit was determined by the domain SOA record, or it was automatically the same as the maximum TTL limit for caching all DNS responses, if configured.