By Manolo Serapio Jr MANILA, April 19 (Reuters) - Nickel futures in Shanghai surged to the highest in almost three years on Thursday, tracking a rally in London prices the session before in what analysts said were misplaced concerns that the metal would also be hit by U.S. sanctions. LME nickel surged to a three-year high on Wednesday as the London Metal Exchange's previously announced move to delist two brands from Russia's Norilsk Nickel, or Nornickel, for delivery against its futu