Twitter Inc. abandoned plans at the 11th hour for a big expansion into Uber and Square’s 1455 Market St. headquarters, potentially due to a hiring slowdown, according to three people with knowledge of the company’s plans. Before putting U.S. expansion plans on hold, the microblog social networking company had nearly finalized a deal with 1455 Market landlord Hudson Pacific Properties (NYSE:HPP) last week to add about 100,000 square feet of former Bank of America office space a block away from…