The restaurant point-of-sale payment flow now uses updated internal method names for payment lines, terminals, and order totals. This keeps the module aligned with the latest platform standards and reduces the risk of future maintenance issues without changing the cashier experience.

In this commit:
- Use the new method names in the payment adjustment flow.
- Replace deprecated snake_case methods with their camelCase equivalents for payment lines, payment terminals, and order totals.

Task:6049128

Forward-Port-Of: odoo/odoo#271792