[CRM] Clean Business Model

- Task: https://www.odoo.com/web#id=8862&view_type=form&model=project.task&menu_id=3942&action=327
- Pad: https://pad.odoo.com/p/r.bMVjkCKLyLgbuEzl
Yeah, you're right @KangOl! 

@tpa-odoo Can you do that for renamed fields?