WASHINGTON — The Trump administration is close to completing one of its biggest rollbacks of environmental rules, replacing a landmark Obama-era effort that sought to wean the nation’s electrical grid off coal-fired power plants and their climate-damaging pollution. The final Trump administration replacement rule, expected as soon as this week, instead would give individual states wide discretion to decide whether to require limited efficiency upgrades at individual coal-fired power plants. The Environmental Protection Agency said Administrator Andrew Wheeler would have a major policy announcement Wednesday but did not disclose the topic.