Refactor ensure_updated_shipments call to be within the OrderContents and OrderPopulator classes to ensure consistency. Fixes #5082

Conflicts:
	core/app/models/spree/order.rb
	core/app/models/spree/order_populator.rb
	core/spec/models/spree/order_populator_spec.rb
	frontend/app/controllers/spree/orders_controller.rb