unbound: improve local zone evaluation in UCI

unbound: improve local zone evaluation in UCI

When UCI local zone is private and static, Unbound covered private
addresses with defaults. Optional delegated global IP6 prefix
protection lacked a static zone, but it was prevented from appearing
in global DNS responses. Domain names router-as-TLD, "lan." and
"local." were static, but they lacked default SOA or NS such as
Unbound had assinged to private addresses. Clean up these local
zones UCI evaluation and block global DNS inclusion.

Signed-off-by: Eric Luehrsen <redacted>