Refactor serve-stale stale-answer-client-timeout 0
Refreshing a stale RRset is similar to a prefetch query, so we can refactor this code to use the new recursion types introduced in !5883 (merged).
Refreshing a stale RRset is similar to a prefetch query, so we can refactor this code to use the new recursion types introduced in !5883 (merged).