By Mark Kleinman Mark Kleinman is Sky News’ City Editor and is the man who gets the Square Mile talking in his weekly City A.M. column. Today, he looks at Entain’s future chief, Legal and General and Dexters Entain’s new CEO will be gambling with careerTalk about a glutton for punishment. I hear that Entain, the FTSE-100 gambling group, is on the brink of putting its chips on its next chief executive. Industry sources tell me that the anointed individual won’t be Henry Birch, the former Rank Group and Very Group boss, who made it to the final stages of the recruitment process. For the moment, …