Remove redundant show_parent=True parameter to usage_results.html and search_results.html

They both ultimately call _list_explore.html with show_parent=1 in all cases

wagtail/wagtailadmin/templates/wagtailadmin/pages/content_type_use.html

@@ -8,7 +8,7 @@
     {% include "wagtailadmin/shared/header.html" with title=pages_str subtitle=page_class.get_verbose_name icon="doc-empty-inverse" %}
    
     <div id="page-results">
-        {% include "wagtailadmin/pages/usage_results.html" with show_parent="True" %}
+        {% include "wagtailadmin/pages/usage_results.html" %}
     </div>
 
 {% endblock %}

wagtail/wagtailadmin/templates/wagtailadmin/pages/search.html

@@ -17,6 +17,6 @@
     {% include "wagtailadmin/shared/header.html" with title=search_str search_url="wagtailadmin_pages_search" icon="search" %}
 
     <div id="page-results">
-        {% include "wagtailadmin/pages/search_results.html" with show_parent="True" %}
+        {% include "wagtailadmin/pages/search_results.html" %}
     </div>
 {% endblock %}