[CRM] Migrate to new API

- Task: https://www.odoo.com/web#id=10543&view_type=form&model=project.task&action=333&active_id=248
- Pad: https://pad.odoo.com/p/r.qE00VdREVpboKWJp
Why 'leads_to_allocate' is a list of 'ids' instead of 'recordsets', Even if you need that recordsets to call a method !!!