Dallas Mayor Eric Johnson taunted Zohran Mamdani over his war on Wall Street — claiming that the Big Apple mayor’s antagonism is accelerating a stampede of businesses down to the booming Texas city. In an exclusive interview with The Post, the Republican mayor of Dallas — the fast-growing metropolis that financiers have branded “Y’all Street” — revealed that the migration of corporate titans out of New York is “only getting stronger” after the first six months of the Mamdani administration. “Mayor Mamdani might be the best thing for Dallas business to ever happen to the city, other than our not having a state income tax,” Johnson quipped. “My message to Mayor Mamdani is, you’re wrong, but keep it coming.” Dallas Mayor Eric Johnson was in New York last month and rang the bell of the New York Stock Exchange along with a delegation of “Y’all Street’ business leaders.…