Remove sponsorship parameters from partner api

CHANGELOG:

### Removed
- [#836](https://gitlab.com/coopdevs/odoo-somconnexio/-/merge_requests/836) Remove sponsorship parameters from partner api

Related card: https://trello.com/c/uqui4WSt/1247-nou-endpoint-per-apadrinaments

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Deploy with https://git.coopdevs.org/coopdevs/som-connexio/odoo-somconnexio-python-client/-/merge_requests/34

and after having deployed https://gitlab.com/coopdevs/migrated-projects/odoo-somconnexio/-/merge_requests/818 with https://git.coopdevs.org/coopdevs/som-connexio/odoo-somconnexio-python-client/-/merge_requests/35