In George Clooney’s brief, conspicuously modest playbill bio for “Good Night, and Good Luck,” the two-time Oscar winner lists none of his many film and television credits. The play’s co-writer and the production’s leading man, Mr. Clooney simply notes that his last time acting in an Equity staging was in 1986; while it was at Chicago’s revered Steppenwolf Theatre, the actor points out that he “has never appeared on Broadway so … buckle up.”