This update removes an unused internal method from the accounting reports area. It has no expected impact on day-to-day reporting, but helps keep the codebase simpler and easier to maintain.

Forward-Port-Of: odoo/enterprise#94732

The Room module’s test setup was updated to stop relying on an old multi-tab service that has been removed elsewhere. This keeps enterprise tests aligned with the main platform changes and reduces maintenance of obsolete internal code.

The community counterpart of this PR removes the legacy multi tab service. This PR adapts the enterprise code to remove it from room's test helpers as well.

task-4984247


community: https://github.com/odoo/odoo/pull/225124.