NEW YORK, Jan 15 (Reuters) - Colonial Pipeline's main U.S. gasoline artery is expected to remain shut through Friday as the company continues to search for the source of a suspected leak in Paulding County, Georgia, the company said in a statement on Wednesday. Line 1, one of two mainlines on the more than 5,500-mile Colonial system, was shut on Monday night after Colonial received reports of a gasoline release. The pipeline moves gasoline from Texas to North Carolina and was earlier expected to resume service on Tuesday night, according to market sources. "Colonial continues on-site work to identify the...