Purpose of this commit is to move moderation tests directly into mail channel test file. That way it is easier to maintain or update them as they are linked to that specific model and not global to mail.thread. Also containing * remove unnecessary tests or merge tests belonging to the same category; * make tests more readable; Followup of odoo/odoo@e9571a4 Followup of odoo/odoo@1fadb3ec5d Task ID-2421795 closes odoo/odoo#64501 Signed-off-by: Thibault Delavallee (tde) <tde@openerp.com>