HOUSTON — Randy Calazans is one of the hottest commodities in Texas right now. He’s a plumber. The winter weather nightmare that swept through the state last week cut off power and heat to millions of homes that were never designed for frigid temperatures. Up and down the state, people were driven from their homes, or came back to find them badly damaged, by pipes and valves and tanks that froze and burst. So when the snow started to defrost and the sun made a coveted return, plumbers were suddenly like roofers after a hurricane: Everybody seemed to need one, all at once. Sign up for The Morning newsletter from the New York Times At One Call Plumbing, the plumbing business where Calazans works, employees have been answering the phones nonstop in a small office with sprawling maps of Houston on the walls. The owner, Edgar Connery, said he had been in the business for nearly 40 years and had never seen a crush like this after other natural disasters. Some other companies ha