Goldman Sachs Group Inc. and Citigroup Inc. are among the banks that have doused companies with debt to an extent that would have been almost unthinkable a year ago, at least for a regulated bank. They’re piling loans onto corporations that are being purchased in leveraged buyouts, and when the dust settles, companies like health-care services provider Envision Healthcare Corp. could have total debt around 7.5 times a measure of earnings. A year ago banks believed, with good reason, that regulators would view any ratio above six times as too high.