fix(ContractMobileTariffChangeWizard): ensure `fiber_linked` is sent
CHANGELOG:
### Fix
- [#1066](https://git.coopdevs.org/coopdevs/som-connexio/odoo-somconnexio/-/merge_requests/1066) Ensure 'fiber_linked' is sent with the code from the selected fiber contract (if sharing data product)
Related card: https://trello.com/c/cqUrOPz3/1701-tiquets-de-ct-sense-fibra-relacionada