Owen Gleiberman Chief Film Critic“The War with Grandpa” opens with a feisty encounter between Robert De Niro and a supermarket scanner. The supermarket has eliminated all its cashiers, and De Niro’s Ed, a senior citizen who wants to check out his cart full of groceries, can’t get the beeping, Siri-voiced scanner to cooperate, which leaves him testy in all the familiar yet agreeably scowling and disgruntled De Niro ways.