It’s Bubba to the rescue! NYPD union leaders think the rift between the rank and file and Mayor Bill de Blasio is so bad, it can only be healed by one man — ex-President Bill Clinton — and police brass are receptive to the idea, sources told The Post. The startling proposal, made during a meeting between Police Commissioner Bill Bratton and the NYPD’s five union chiefs on Wednesday, came as a shot cop got a hero’s send-off upon being released from the hospital.