Remove outdated "import _self as" tag

Problem/Motivation

We have some outdated Twig1 code:

Branch 4.x:

templates/patterns/pagination/pattern-pagination.html.twig:{% import _self as pagination %}
templates/patterns/navbar/pattern-navbar.html.twig:  {% import _self as menus %}

Branch 5.x:

templates/patterns/navbar_nav/pattern-navbar-nav.html.twig:  {% import _self as menus %}
templates/patterns/pagination/pattern-pagination.html.twig:{% import _self as pagination %}

Since Twig 2, it is not necessary to import explicitly _self in variable :

{% macro item(whatever) %}...{% endmacro %}
{% import _self as pagination %}
{{ pagination.item(whatever) }}

Because it is now possible to call a macro directly from _self:

{% macro item(whatever) %}...{% endmacro %}
{{ _self.item(whatever) }}

Source : https://twig.symfony.com/doc/2.x/tags/macro.html

Proposed resolution

Remove "import _self as" tags

For 4.x, push directly the commit. For 5.x, do a MR.

API changes

None because:

• Drupal 9.x use Twig 2.x : https://git.drupalcode.org/project/drupal/-/blob/9.5.x/core/composer.json
• Drupal 10.x use Twig 3.x : https://git.drupalcode.org/project/drupal/-/blob/10.1.x/core/composer.json