SAN DIEGO — The National Association of Immigration Judges on Thursday asked the federal government to restore its union recognition after the Trump administration stripped its official status and the system’s chief judge resigned after two years on the job.The two developments come at a critical time for the Justice Department’s Executive Office for Immigration Review, which runs the courts.The judges’ backlog of immigration cases has tripled to 1.8 million since 2017. Cases for people who are not …