chore: 调整dns interface与adapter部分

dns/util.go

@@ -3,7 +3,6 @@ package dns
 import (
 	"context"
 	"crypto/tls"
-	"errors"
 	"fmt"
 	"net"
 	"net/netip"
@@ -20,8 +19,6 @@ import (
 	D "github.com/miekg/dns"
 )
 
-var errProxyNotFound = errors.New("proxy adapter not found")
-
 func putMsgToCache(c *cache.LruCache[string, *D.Msg], key string, msg *D.Msg) {
 	var ttl uint32
 	switch {