Katie Holmes headed to LA just before the Oscars for a 24-hour trip. Spies saw her at an exclusive dinner Thursday hosted by ICM Partners, the agency she joined after defecting from CAA last month. Also at the private party were “Les Misérables” director Tom Hooper, Oscar nominee Christoph Waltz and Jay Pharoah of “SNL.” “It was like Katie’s return to Hollywood,” a spy said of the actress, who has kept close to New York since her split from Tom Cruise. She headed back to the Big Apple before the awards.