While John DeStefano’s gubernatorial campaign trumpets a thumbs-up from Lt. Gov. Kevin Sullivan, they’ve been curiously mum on an endorsement from another longtime Democratic powerbroker: Ed Marcus, who has returned from political exile in New Haven. The lawyer and former state party chairman has patched up his spat with Mayor John DeStefano and endorsed DeStefano’s bid for governor. Now Marcus is working on New Haven taxpayers’ dime again, though DeStefano said he had no part in that decision.