WASHINGTON — The Supreme Court has stopped the Biden administration from enforcing a requirement that employees at large businesses be vaccinated against COVID-19 or undergo weekly testing and wear a mask on the job.At the same time, the court is allowing the administration to proceed with a vaccine mandate for most health care workers in the U.S.The court’s orders Thursday during a spike in coronavirus cases was a mixed bag for the administration’s efforts to boost the vaccination rate among Americans.The court’s …