Issue 6769 - Avoid hardcoding the URL

pages/filters/blocking.tmpl

 title = Blocking
 template = testcase
 
 {% set testcase_moreinfo = [
   ("Filter Cheatsheet - Blocking", "https://adblockplus.org/filter-cheatsheet#blocking"),
 ] %}
 
 <section class="site-panel">
   <h2>Blocking</h2>
   <p>Check that basic blocking functionality is working as expected.</p>
   <p>With the filter displayed below each test case added to ABP (or with the testcase subscription installed and active), the test images in each test case panel should be blocked.</p>
 </section>
 
 <section class="site-panel">
   <h2>Complete Address</h2>
   <div class="testcase-container">
     <img class="testcase-contentaside blocked" src="/testcasefiles/blocking/addresscomplete/image.jpg">
     <div class="testcase-content stripes-grey">Content</div>
   </div>
   <h3>Filters</h3>
-  <pre>||testpages.adblockplus.org/testcasefiles/blocking/addresscomplete/image.jpg</pre>
+  <pre>||{{ site_url|strip_proto }}/testcasefiles/blocking/addresscomplete/image.jpg</pre>
 </section>
 
 <section class="site-panel">
   <h2>Part Address</h2>
   <div class="testcase-container">
     <img class="testcase-contentaside blocked" src="/testcasefiles/blocking/addresspart/abptestcasepath/image.jpg">
     <div class="testcase-content stripes-grey">Content</div>
   </div>
   <h3>Filters</h3>
   <pre>/testcasefiles/blocking/addresspart/abptestcasepath/</pre>
 </section>
 
 <section class="site-panel">
   <h2>Wildcard</h2>
   <div class="testcase-container">
     <img class="testcase-contentaside blocked" src="/testcasefiles/blocking/wildcard/one/image.jpg">
     <img class="testcase-contentaside blocked" src="/testcasefiles/blocking/wildcard/two/image.jpg">
     <div class="testcase-content stripes-grey">Content</div>
   </div>
   <h3>Filters</h3>
-  <pre>||testpages.adblockplus.org/testcasefiles/blocking/wildcard/*/image.jpg</pre>
+  <pre>||{{ site_url|strip_proto }}/testcasefiles/blocking/wildcard/*/image.jpg</pre>
 </section>