DEV: removes deprecated code (#23183)

plugins/chat/assets/javascripts/discourse/chat-route-map.js

@@ -1,10 +1,5 @@
 export default function () {
   this.route("chat", { path: "/chat" }, function () {
-    // TODO(roman): Remove after the 3.1 release
-    this.route("channel-legacy", {
-      path: "/channel/:channelId/:channelTitle",
-    });
-
     this.route("channel", { path: "/c/:channelTitle/:channelId" }, function () {
       this.route("near-message", { path: "/:messageId" });
       this.route("threads", { path: "/t" });

plugins/chat/assets/javascripts/discourse/routes/chat-channel-decorator.js

@@ -31,19 +31,10 @@ export default function withChatChannel(extendedClass) {
         return this.router.replaceWith("chat");
       }
 
-      let { messageId, channelTitle } = this.paramsFor(this.routeName);
-
-      // messageId query param backwards-compatibility
-      if (messageId) {
-        this.router.replaceWith(
-          "chat.channel",
-          ...model.routeModels,
-          messageId
-        );
-      }
+      let { channelTitle } = this.paramsFor(this.routeName);
 
       if (channelTitle && channelTitle !== model.slugifiedTitle) {
-        messageId = this.paramsFor("chat.channel.near-message").messageId;
+        const messageId = this.paramsFor("chat.channel.near-message").messageId;
         const threadId = this.paramsFor("chat.channel.thread").threadId;
 
         if (threadId) {

plugins/chat/lib/chat/user_notifications_extension.rb

@@ -44,19 +44,9 @@ module Chat
       build_summary_for(user)
       @preferences_path = "#{Discourse.base_url}/my/preferences/chat"
 
-      # TODO(roman): Remove after the 2.9 release
-      add_unsubscribe_link = UnsubscribeKey.respond_to?(:get_unsubscribe_strategy_for)
-
-      if add_unsubscribe_link
-        unsubscribe_key = UnsubscribeKey.create_key_for(@user, "chat_summary")
-        @unsubscribe_link = "#{Discourse.base_url}/email/unsubscribe/#{unsubscribe_key}"
-        opts[:unsubscribe_url] = @unsubscribe_link
-      end
-
       opts = {
         from_alias: I18n.t("user_notifications.chat_summary.from", site_name: Email.site_title),
         subject: summary_subject(user, @grouped_messages),
-        add_unsubscribe_link: add_unsubscribe_link,
       }
 
       build_email(user.email, opts)

plugins/chat/plugin.rb

@@ -425,7 +425,6 @@ after_initialize do
   end
 
   on(:category_updated) do |category|
-    # TODO(roman): remove early return after 2.9 release.
     # There's a bug on core where this event is triggered with an `#update` result (true/false)
     if category.is_a?(Category) && category_channel = Chat::Channel.find_by(chatable: category)
       if category_channel.auto_join_users