PHILADELPHIA — An exasperated Philadelphia Mayor Jim Kenney said early Tuesday morning after two police officers were shot that he is so worried about safety at public events that he will “be happy” when he is no longer the mayor. Standing alongside police brass outside Thomas Jefferson University Hospital, Kenney made the comments just after midnight, about two hours after gunfire rang out and chaos ensued during the city’s annual Independence Day celebration on the Benjamin Franklin Parkway. “There’s not an event or a day where I don’t lay on my back at night, looking at the ceiling and worr…