Use a more conservative strategy for resolving with systemd-resolved for local DNS server

dns/transport/local/local_resolved_stub.go

@@ -9,6 +9,10 @@ import (
 	"github.com/sagernet/sing/common/logger"
 )
 
+func isSystemdResolvedManaged() bool {
+	return false
+}
+
 func NewResolvedResolver(ctx context.Context, logger logger.ContextLogger) (ResolvedResolver, error) {
 	return nil, os.ErrInvalid
 }