Eager load topics. Avoid n+1

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

Author: fbacall

app/views/learning_paths/show.html.erb

@@ -61,8 +61,8 @@
       </div>
 
       <div class="learning-path-topics">
-        <% topics = @learning_path.topic_links.joins(:topic) %>
-        <% topic_count = topics.count %>
+        <% topics = @learning_path.topic_links.includes(topic: :material_items).load %>
+        <% topic_count = topics.size %>
         <% topics.each do |lpt| %>
           <% classes = ['learning-path-topic'] %>
           <% classes << 'single-topic' if topic_count == 1 %>