fix(MobileContractProcess): set shared_bond_id to False if OTRS sends {}

CHANGELOG:

### Fixed
- [#1067](https://git.coopdevs.org/coopdevs/som-connexio/odoo-somconnexio/-/merge_requests/1067) 

Related card: https://trello.com/c/ojrME1qp/1699-cas-concret-opci%C3%B3-compartides-no-disponible-a-wizard-compartides-odoo

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