Punctuation fieldset is too long

Steps to reproduce:
1. Install pathautho module.
2. Go to admin page /admin/config/search/path/settings.
3. Scroll down the page.

We can see that "Punctuation" fieldset is open and it's very-very long! I couldn't make a screen because it's too long for this!

Let's take a look at the code:

 $form['punctuation'] = array(
    '#type' => 'fieldset',
    '#title' => $this->t('Punctuation'),
    '#collapsible' => TRUE,
    '#collapsed' => TRUE,
    '#tree' => TRUE,
  );

Looks like it supposed to be hidden, but... collapsible fieldsets have been replaced with HTML5 details elements. See change records for details.