[FIX] sale_timesheet: prevent multicompany issue on SOL

Steps to reproduce:

        - Create an SO for a prepaid service in company A and confirm it
        - Create a project and a task in company B and select the customer linked to the SO you previously created
        - Unselect company A from the multi-company widget; only display the records from company B
        - Timesheet on the task you previously created

Observed behavior:

        - The SOL set by default belongs to company A, thus generating an access right error when trying to timesheet on the task

Expected behavior:

        - The SOL set by default should belong to the same company as the task

task-2515259

closes odoo/odoo#69783

Related: odoo/enterprise#17921
Signed-off-by: Yannick Tivisse (yti) <yti@odoo.com>