Amazon CEO Andy JassyREUTERS/Mike Blake; Chelsea Jia Feng/BIAmazon CEO Andy Jassy led a turnaround by changing habits and assumptions under founder Jeff Bezos.Jassy slashed costs, won over Wall Street, and put a new stamp on Amazon's culture."I'd rather have Jassy than Bezos," one top Amazon investor told BI.In November 2022, roughly a dozen top Amazon investors convened in a large conference room at the company's Seattle headquarters.They were …