WASHINGTON — Tens of thousands of immigrants who are in the U.S. illegally but don’t have serious criminal records could be shielded from deportation under a policy change being weighed by Homeland Security Secretary Jeh Johnson. The change, if adopted following a review ordered by President Barack Obama, could limit removals of people who have little or no criminal record but have committed repeat immigration violations such as re-entering the country illegally after having been deported or failing to …