fix(adguard): disable DNS request rate limit

The private resolver grouped clients by IPv4 /24 and silently dropped requests above 20 queries per second. Disable the public-server protection so internal DNS bursts complete.

configs/nixos/modules/services/adguardhome.nix

@@ -47,10 +47,7 @@ in
           bind_hosts = [ "0.0.0.0" ];
           port = 53;
           anonymize_client_ip = false;
-          ratelimit = 20;
-          ratelimit_subnet_len_ipv4 = 24;
-          ratelimit_subnet_len_ipv6 = 56;
-          ratelimit_whitelist = [ ];
+          ratelimit = 0;
           refuse_any = true;
           upstream_dns = [
             "https://dns.cloudflare.com/dns-query"