Move grouped notes into severity tooltip

styles/audit.css

@@ -290,6 +290,10 @@
   min-width: 0;
 }
 
+.storage-audit__severity--hint {
+  cursor: help;
+}
+
 .severity-high .storage-audit__severity {
   background: color-mix(in srgb, #b03e29 80%, transparent);
   color: white;