[IMP] partner_autocomplete: simplify some marshmalling code for IAP data

Purpose is to achieve more readable code.

LINKS

Task ID-2322455
PR #64600
PR odoo/upgrade#2086

Co-Authored-By: David Beguin <dbe@odoo.com>
Co-Authored-By: Thibault Delavallee <tde@odoo.c>