The update changes how chatter areas are managed internally across several Odoo apps, removing an outdated registration method. This helps keep messaging behavior more consistent and easier to maintain without changing day-to-day user workflows.

*: documents, stock_barcode, web_studio.

No container should be registered as messaging component. ChatterContainer is the
last one registering itself as such. This PR solves this issue.

community: https://github.com/odoo/odoo/pull/92541

This update adjusts internal payment-related test tools to stay compatible with recent changes in the shared Odoo codebase. It helps keep automated checks reliable for payment flows, including SEPA direct debit and subscription payments, without changing day-to-day user functionality.

COM PR: https://github.com/odoo/odoo/pull/90716

Belgian reporting checks were updated to align with revised tax names, helping keep report validation accurate. Studio also now recognizes the tax tag widget, making it easier to configure tax-related fields consistently.

This PR:
- updates the tests for Belgian reports to fit the new tax names
- adds the new `many2many_tags_tax` widget to Studio

Community PR: https://github.com/odoo/odoo/pull/91667