Issue 6769 - Avoid hardcoding the URL

pages/exceptions/stylesheet.tmpl

 title = $stylesheet Exception
 template = testcase
 
 {% set testcase_moreinfo = [
   ("Filter Options", "https://adblockplus.org/filters#options"),
 ] %}
 
 <link rel="stylesheet" href="/testcasefiles/stylesheetexception/stylesheet.css">
 
 <section class="site-panel">
   <h2>$stylesheet Exception</h2>
   <p>Check that usage of the $stylesheet filter option in an exception filter works as expected.</p>
   <p>With the filter(s) displayed below each test case added to ABP (or with the testcase subscription installed and active), the image should be blocked while the stylesheet should not be.</p>
 </section>
 
 <section class="site-panel">
   <h2>Test case</h2>
   <div class="testcase-container">
     <div class="testcase-row">
       <h3>Image</h3>
       <img class="blocked" src="/testcasefiles/stylesheetexception/image.jpg"/>
     </div>
     <div class="testcase-row">
       <h3>Stylesheet</h3>
       <div class="testcase-teststylesheet"></div>
     </div>
   </div>
   <h3>Filters</h3>
-  <pre>||testpages.adblockplus.org/testcasefiles/stylesheetexception/*</pre>
-  <pre>@@testpages.adblockplus.org/testcasefiles/stylesheetexception/$stylesheet</pre>
+  <pre>||{{ site_url|strip_proto }}/testcasefiles/stylesheetexception/*</pre>
+  <pre>@@{{ site_url|strip_proto }}/testcasefiles/stylesheetexception/$stylesheet</pre>
 </section>