The admin toolbar menu depth option is not taken into consideration

Problem/Motivation

#3200542: Make menu depth configurable → added an option to make the admin menu depth configurable. This option is not yet being considered in Drupal\amswap\Render\Element\Amswap::preRender().

Proposed resolution

Get the menu depth from \Drupal::config('admin_toolbar.settings')->get('menu_depth').