[Odometer] Refactor IOURequestStepDistanceOdometer to use handleMoneyRequestStepDistanceNavigation

[Julesssss]

Part of the Migrate Odometer project.

IOURequestStepDistanceOdometer contains ~100 lines duplicating logic for participant selection, skip-confirmation handling, and navigation that already exists in handleMoneyRequestStepDistanceNavigation. This helper centralizes the "what happens after distance is set" flow.

Refactor to call handleMoneyRequestStepDistanceNavigation after saving odometer readings. Only odometer-specific code (storing readings and passing them to request/track payload) should remain.