This change removes unused code from the field service sales area. It helps keep the system easier to maintain without changing how users work with the product.

Removing the dead code

The Documents Accounting app no longer includes the old Tax Statement and Financial Statement activity types. These reminders were tied to an earlier workflow for accounting firms and have been replaced by newer accounting returns functionality, reducing clutter for users.

Remove {Tax, Financial} Statement activity types. There were linked to development targetting *fiduciaires* but are nox replaced by better feature, notably accounting returns feature.

Followup of odoo#206592

Task-4592571