Do not add milter headers for authenticated users

data/conf/rspamd/local.d/milter_headers.conf

@@ -1,6 +1,6 @@
 use = ["spam-header", "x-spamd-result", "x-rspamd-queue-id", "authentication-results"];
 skip_local = false;
-skip_authenticated = false;
+skip_authenticated = true;
 routines {
   spam-header {
     header = "X-Spam-Flag";