WASHINGTON — When a proposal to encourage end-of-life planning touched off a political storm over “death panels,” Democrats dropped it from legislation to overhaul the health care system. But the Obama administration will achieve the same goal by regulation, starting Jan. 1. Under the new policy, outlined in a Medicare regulation, the government will pay doctors who advise patients on options for end-of-life care, which may include advance directives to forgo aggressive life-sustaining treatment.