By Katanga Johnson WASHINGTON (Reuters) -The U.S. Securities and Exchange Commission (SEC) on Monday proposed new rules aimed at preventing conflicts of interest in management and governance of clearing houses. Clearing houses provide essential plumbing for financial markets, ensuring that securities or derivatives trades are completed, even if one side of a transaction goes bust. Under the SEC’s proposal, registered clearing houses would be required to disclose more details on board composition, independent directors, and nominating and risk management committees, among other details, the age…