Issue 5757 - Update buildtools dependency, (re)move legacy extensions

sitescripts/extensions/template/nightlies.html

 <!--
   - This file is part of the Adblock Plus web scripts,
   - Copyright (C) 2006-present eyeo GmbH
   -
   - Adblock Plus is free software: you can redistribute it and/or modify
   - it under the terms of the GNU General Public License version 3 as
   - published by the Free Software Foundation.
   -
   - Adblock Plus is distributed in the hope that it will be useful,
   - but WITHOUT ANY WARRANTY; without even the implied warranty of
@@ skipping 10 matching lines @@
 
 <p style="border: 1px solid black; background-color: #FEE; color: #000; margin-left: 5px; margin-right: 5px; padding: 5px;">
   <strong>Warning</strong>: The files in this directory are development
   builds and as such they have not been fully tested and might not work
   properly.
 
   Use them at your own risk, see <a href="https://adblockplus.org/en/development-builds">development builds introduction</a> for more information.
 
   {%if config.galleryID or config.downloadPage -%}
   Latest <em>stable {{config.name}} release</em> can be downloaded from
-  {% if config.type in ['gecko', 'gecko-webext'] and config.galleryID -%}
+  {% if config.type == 'gecko' and config.galleryID -%}
     <a href="https://addons.mozilla.org/addon/{{config.galleryID}}/">Mozilla Add-ons</a>
   {%- elif config.type == 'chrome' and config.galleryID -%}
     <a href="https://chrome.google.com/webstore/detail/{{config.galleryID}}">Chrome Web Store</a>
   {%- else %}
     <a href="https://adblockplus.org{{config.downloadPage}}">its installation page</a>
   {%- endif -%}
   .
   {%- endif %}
 </p>
 
 <h2>Development build listing for {{config.name}}</h2>
 <hr />
 <table border="0" cellspacing="10">
 {%- for link in links %}
 <tr{%if loop.first%} style="font-weight: bold;"{%endif%}>
   <td>
     <a href="{{link.download}}">{{config.name}} {{link.version}}</a>
     {%- if link.changelog %}
       <a href="{{link.changelog}}"> (changelog)</a>
     {%- endif %}
   </td>
   <td>{{link.mtime|formattime}}</td>
   <td>{{link.size|bytes}}</td>
 </tr>
 {%- endfor %}
 </table>
 <hr />
 </body>
 </html>