(Reuters) -AT&T investors will watch out on Wednesday for comments from top management on the telecom firm's financial and legal liability for the lead-clad cables it abandoned decades ago that may have contaminated soil and water sources across the United States. The $100-billion company last week said lead-clad cables made up only a "small part of its network" as it sought to allay investor apprehensions. Still, shares have yet to fully recover from a tumble to a three-decade low following a Wall Street Journal report that several U.S. telecom giants including Verizon h...