AMBARI-4501. health status yellow (lost heartbeat) not showing icon. (onechiporenko)

ambari-web/app/styles/application.less

@@ -2779,6 +2779,8 @@ table.graphs {
     .status-dot-position;
   }
   .health-status-DEAD-YELLOW {
+    background-image: @status-dead-yellow-marker;
+    .status-dot-position;
   }
   .passive-state {
     color: #000;