What are these Wall Street titans afraid of, exactly? Jamie Dimon and David Solomon — maybe the two most powerful bankers in New York — are invariably described as “tough,” “no nonsense” and “hard-charging.” Yet when they each met up last week with the city’s socialist mayor, Zohran Mamdani , you’d think they had just toured a rose garden with Xi Jinping . Dimon and Mamdani held a “friendly” and “constructive dialogue” on Monday, a JPMorgan source told me. The pair chatted about the need for “