/modules/mod_articles_category/helper.php and search plugin require content router file

[Denitz]

Steps to reproduce the issue

See /modules/mod_articles_category/helper.php:

require_once $com_path . 'router.php';

See /plugins/search/content/content.php:
require_once JPATH_SITE . '/components/com_content/router.php';

Expected result

Component router file is included in router but should not be included directly, otherwise router override is impossible.

Actual result

Included directly.

System information (as much as possible)

Additional comments

[Denitz]

PR:
#5437