Reduce rspamd DNS timeout

Fixes #1957

data/conf/rspamd/local.d/options.inc

@@ -3,7 +3,7 @@ dns {
 }
 map_watch_interval = 30s;
 dns {
-  timeout = 15s;
-  retransmits = 5;
+  timeout = 4s;
+  retransmits = 2;
 }
 disable_monitoring = true;