The Washington National Opera, which opened its production of Robert Ward’s “The Crucible” (1961) on Saturday, did not expect to be presenting some of its 70th-anniversary season back where it started, in George Washington University’s 1,482-seat Lisner Auditorium. But WNO’s situation at its Kennedy Center home following President Trump’s takeover of the venue last year became increasingly untenable. Artists canceled, donors and audience members stayed away, the Center’s staff was slashed, and its new president, Richard Grenell, demanded a “revenue neutral” model for every show, meaning each one had to pay for itself, an impossible task for an opera company. As contingency planning last summer, the company embarked on a stealth tour of potential venues for its season’s operas, and on Jan. 9 it announced that it would leave the Center after 55 years in residence. “We had soft holds on the venues,” says Francesca Zambello, the company’s artistic director. “On Jan. 10, we locked them down.”