Carl Icahn, the subject of countless name-checks by Donald Trump during the 2016 campaign, today joined a host of other business leaders who are jumping off of the MAGA train. The billionaire investor and veteran pot stirrer sent POTUS a letter saying he is leaving his unofficial presidential advisory post because he “did not want partisan bickering about my role to in any way cloud your administration.” Read the letter in full below. Soon after Icahn was named as Trump’s…