FIX: Display summaries for anonymous users. (#23294)

Streaming doesn't work for anonymous users because we scope updates to the current user. Since they can only see cached summaries, we can skip the streaming parameter and update it directly with the ajax response.

app/controllers/topics_controller.rb

@@ -1185,7 +1185,7 @@ class TopicsController < ApplicationController
 
     opts = params.permit(:skip_age_check)
 
-    if params[:stream]
+    if params[:stream] && current_user
       Jobs.enqueue(
         :stream_topic_summary,
         topic_id: topic.id,