Jared Kushner’s immigrant grandparents survived on a slew of benefits the type of which his father-in-law, former President Donald Trump, has already weakened and threatens to dismantle, according to a new report. Kushner’s grandmother Rae and grandfather Joseph Berkowitz — who fled the Holocaust after World War II — were brought to the U.S. and supported financially by programs Trump commonly attacks, the Washington Post reported Monday. “Seven decades later, their grandson became a top official in an administration that sharply restricted immigration and cut the number of refugees the countr…