PERF: do not include suggested topics when loading new posts

When a new post is triggered via message bus post stream will attempt to load
it, previously the `/topic/TOPIC_ID/posts.json` would unconditionally include
suggested topics, this caused excessive load on the server.

New pattern defaults to exclude suggested and related topics from this API
unless people explicitly ask for suggested.

lib/topic_view.rb

@@ -51,6 +51,9 @@ class TopicView
     @post_number = [@post_number.to_i, 1].max
     @page = [@page.to_i, 1].max
 
+    @include_suggested = options.fetch(:include_suggested) { true }
+    @include_related = options.fetch(:include_related) { true }
+
     @chunk_size =
       case
       when @print then TopicView.print_chunk_size
@@ -402,11 +405,19 @@ class TopicView
   end
 
   def suggested_topics
-    @suggested_topics ||= TopicQuery.new(@user).list_suggested_for(topic, pm_params: pm_params)
+    if @include_suggested
+      @suggested_topics ||= TopicQuery.new(@user).list_suggested_for(topic, pm_params: pm_params)
+    else
+      nil
+    end
   end
 
   def related_messages
-    @related_messages ||= TopicQuery.new(@user).list_related_for(topic, pm_params: pm_params)
+    if @include_related
+      @related_messages ||= TopicQuery.new(@user).list_related_for(topic, pm_params: pm_params)
+    else
+      nil
+    end
   end
 
   # This is pending a larger refactor, that allows custom orders