Fix current tier highlight on fee waiver (#11816)

Author: Luke-Oldenburg

app/views/events/perks/_fee_waiver.html.erb

@@ -35,7 +35,7 @@
         <td>5-9 active teenagers</td>
         <td>3.5% fee</td>
       </tr>
-      <tr class="<%= "card__darker" if active_teenagers_count > 10 %>">
+      <tr class="<%= "card__darker" if active_teenagers_count >= 10 %>">
         <td>10+ active teenagers</td>
         <td>0.0% fee</td>
       </tr>