[2.0.0-beta1] drawer component: simpler attributes management

Problem/Motivation

Thanks to 📌 Prevent TypeError when using create_attribute Twig function Fixed , this

      {% set item_attributes = item.attributes|default({}) %}
      {% set item_attributes = item_attributes.storage() is defined ? item_attributes : create_attribute(item_attributes) %}

Proposed resolution

Try to replace it with:

 {% set item_attributes = create_attribute(item.attributes|default({}) %}