The restaurant point of sale payment flow now uses the latest internal method names for payment lines, terminals, and order totals. This keeps the module aligned with current platform standards and helps prevent future compatibility issues without changing the customer-facing workflow.

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