Defaults UI page has malformed html markup

Problem/Motivation

The markup on /admin/config/search/metatag is malformed which causes browsers to make a best guess about how to render the page. This is especially problematic when doing testing based on content within a specific html structure.

Steps to reproduce

Go to /admin/config/search/metatag and view the html source code (not in devtools. Devtools will do its best to correct it).

You will see markup like:

<details class="js-form-wrapper form-wrapper seven-details">
  <summary role="button" aria-expanded="false" aria-pressed="false" class="seven-details__summary">
    <span>Global</span>
  </summary>
  <div class="seven-details__wrapper details-wrapper">
    <div>
      <table>
        <tbody>
          <tr><td>canonical_url:</td><td>[current-page:url]</td></tr>
          <tr><td>title:</td><td>[current-page:title] | [site:name]</td></tr>
        </tbody>
      </table>
    </div>
  </div>
</div></details>

Proposed resolution

Remove the extra closing </div> before the </details> on src/MetatagDefaultsListBuilder.php