fix: Fixes the problem with _load_textdomain_just_in_time

[fabianmossberg]

Moving load_textdomain from plugins_loaded to init.

Closes #2545

[spacecharly]

This is the solution to fix the notice "Function _load_textdomain_just_in_time was called incorrectly. Translation loading for the kirki domain was triggered too early"

It is necessary to use the 'init' hook instead of the 'plugins_loaded' hook for loading text domains to align with WordPress 6.7 requirements, which specify that text domains should only be loaded on init or later.