FIX: prevent default event on touchend reaction (#22588)

This was causing this event to cause other touch events down the road. For example click a reaction above the composer when the message action was opened could cause the composer to gain focus after the reaction was made.

plugins/chat/assets/javascripts/discourse/components/chat-message-reaction.js

@@ -90,6 +90,8 @@ export default class ChatMessageReaction extends Component {
 
   @action
   onTouchEnd(event) {
+    event.preventDefault();
+
     if (this.touching) {
       this.handleClick(event);
     }