Update metrics.conf

data/conf/rspamd/local.d/metrics.conf

@@ -33,9 +33,4 @@ group "MX" {
 	  description = "MX was ok";
 	  one_shot = "true";
 	}
-	symbol "MX_IMPLICIT" {
-	  score = -2.0;
-	  description = "MX not defined but A record at apex";
-	  one_shot = "true";
-	}
 }