event-rule-details.less: Remove unused `. new-event-rule

Author: flourish86

public/css/detail/event-rule-detail.less

@@ -362,10 +362,6 @@
   width: 14.5em;
 }
 
-.new-event-rule {
-  margin-bottom: 1em;
-}
-
 .event-rule-and-save-forms {
   display: flex;
   flex-wrap: wrap;