[Rspamd] rename symbol from bad_regex to bad_subject

data/conf/rspamd/local.d/metadata_exporter.conf

@@ -51,7 +51,7 @@ return function(task)
     and not task:has_symbol('GLOBAL_MIME_FROM_BL')
     and not task:has_symbol('LOCAL_BL_ASN')
     and not task:has_symbol('GLOBAL_RCPT_BL')
-    and not task:has_symbol('BAD_REGEX_00')
+    and not task:has_symbol('BAD_SUBJECT_00')
     and not task:has_symbol('MAILCOW_BLACK') then
       local action = task:get_metric_action('default')
       if action == 'reject' or action == 'add header' or action == 'rewrite subject' then