[FIX] crm: Problem when entering or removing tags on some opportunities

Steps to reproduce the bug:

- With Studio add fields: Prorated revenue, Followers (Partners) in the view crm.lead view form
- With Studio add field: Created on on res.partner view form
- Try to edit an existing opportunity by changing Expected revenue

Bug:

A traceback was raised because NewId was in self

opw:2613125

closes odoo/odoo#74854

Signed-off-by: Simon Goffin (sig) <sig@openerp.com>