Improve ordering of UI elements

EDIT - I said it wrong earlier:

There's code above the $form['force_auto'] = [definition] lines, which adds states, which is now useless (because it's overwritten by the later definition):

    if ($layout_builder_enabled) {
      $form['force_auto']['#states'] = [
        'visible' => [
          ':input[name="force_layout"]' => ['checked' => FALSE],
        ],
      ];
    }

I will move that down too, because I still believe that it's useful to make this checkbox invisible when layout builder is being enabled. (It gives the user a better sense of what is happening.)

But I'll do that in #3471568: "Use layout builder" option is not saved - which is a mistake that deserves its separate issue title.