Guardant Health Inc.agreed to pay more than $900,000 to settle allegations that the company’s human resources office hired a relative and a friend of a physician who persuaded the company to make the hires in a quid pro quo for orders of Guardant’s tests. The U.S. Department of Justice said the penalties could have been much greater but for the company’s cooperation in the investigation, which disclosed that at least one of these hires was not qualified for the position.