Replace `blog_cards.html` with `entry_cards.html`

The former was only used once. And its use would basically just end up
being a copy of the latter anyhow. The `blog_cards.html` is now removed
in favor of the `entry_cards.html` template.

network-api/networkapi/wagtailpages/templates/wagtailpages/fragments/blog_cards.html

@@ -1,5 +0,0 @@
-{% load wagtailcore_tags %}
-
-{% for page in entries %}
-{% include "./blog_card.html" %}
-{% endfor %}

network-api/networkapi/wagtailpages/templates/wagtailpages/fragments/related_posts.html

@@ -9,11 +9,9 @@
 
       <div class="related-posts mb-4">
         <div class="row">
-          {% include "./blog_cards.html" with entries=related_posts %}
-          </div>
+          {% include "./entry_cards.html" with entries=related_posts %}
         </div>
       </div>
-
     </div>
   {% endif %}
 {% endblock %}