This update resolves an issue where a crucial component was missing from the French tax report XML. The addition of the custom handler model ensures accurate generation of the 2031 and 2031 annexes tax reports, aligning with French tax regulations. This ensures compliance and accurate reporting.

The PR #108522 introduced new 2031 and 2031 annexes tax report for FR. But in the 2031 report XML, custome handler model was not added.

This PR adds the corresponding custom handler model.

Forward-Port-Of: odoo/enterprise#116373