Anthem Inc. and the U.S. Justice Department extended their clash over whether the insurer’s planned takeover of rival Cigna Corp. will raise costs, as government witnesses testified Friday that the deal will harm health-care providers and patients. Frank Gorse, a vice president at Patient First, which operates urgent-care centers in the Mid-Atlantic region, said he’s concerned the merger will squeeze providers due to Anthem’s lower payouts, harming patient services.