LOS ANGELES — Just a few months ago, California was the epicenter of the coronavirus pandemic in the U.S. Hospitals in Los Angeles were drowning in patients, and ambulances were idling outside with people struggling to breathe, waiting for beds to open. The death count was staggering — so many that morgues filled and refrigerated trucks were brought in to handle the overflow. Now as cases spike in other parts of the country, California has gone from worst to first with the lowest infection rate in the U.S. even as it has moved quickly to reopen more businesses with greater customer counts and allow larger gatherings.