FIX: emoji-picker minor improvements (#30645)

- uses emojiSearch to ensure we have the same result than autocomplete when filtering emojis (for example search aliases were not working correctly because of this)
- reset the visible sections when clearing filter to ensure we are not attempting to display all the emojis at once which would be slow
- prevents flashing of the full emoji list before showing filtered results
- correctly reset recent favorites and only show them when used

plugins/chat/assets/javascripts/discourse/components/chat-message-actions-desktop.gjs

@@ -28,6 +28,7 @@ const REDUCED_WIDTH_THRESHOLD = 500;
 export default class ChatMessageActionsDesktop extends Component {
   @service chat;
   @service site;
+  @service siteSettings;
   @service emojiStore;
 
   @tracked size = FULL;
@@ -35,8 +36,13 @@ export default class ChatMessageActionsDesktop extends Component {
   popper = null;
 
   get favoriteReactions() {
+    const defaultReactions = this.siteSettings.default_emoji_reactions
+      .split("|")
+      .filter(Boolean);
+
     return this.emojiStore
       .favoritesForContext(`channel_${this.message.channel.id}`)
+      .concat(defaultReactions)
       .slice(0, 3)
       .map(
         (emoji) =>