It’s T-minus Mother’s Day at your favorite lavish, all-you-can-eat brunch place. Chefs will admit that for weeks, cooks have been cutting off the unappetizing ends of ham and tossing them into the freezer for that “Deluxe Omelet Bar.” Sauces, made several days ago, already are congealing in the walk-in. Chimichangas, made on Thursday and getting soggier by the minute, are waiting for their turn to be revived in the deep fryer. And housekeeping has stocked bathroom stalls with plenty of full