Fixes 6546 - Swap the contents of default.tmpl and empty.tmpl in the test suite

tests/test_site/pages/sitemap.tmpl

-template = empty 
 product = foo
 title = test_metadata
 tags = [popular, bar]
 <h1> Unfiltered </h1>
 <ul>
 {%- for unfiltered_page in get_pages_metadata()|sort %}
   <li>title : {{ unfiltered_page['page']}} </li>
 {%- endfor %}
 </ul>
 
 <h1> Filtered </h1>
 <ul>
     {%- for filtered_page in get_pages_metadata({'tags': ['popular', 'bar']})|sort -%}
         <li>title : {{ filtered_page['page'] }} </li>
 {%- endfor %}
 </ul>
 
 <h1> String Filter For Listy Option </h1>
 <ul>
     {%- for filtered_page in get_pages_metadata({'tags': 'popular'})|sort -%}
         <li>title : {{ filtered_page['page'] }} </li>
 {%- endfor %}
 </ul>