(Reuters) - Kraft Heinz Co fell short of Wall Street expectations for quarterly sales on Thursday as the struggling packaged food company battled weak demand in the United States, its biggest market.Net income attributable to the company's shareholders rose to $899 million (£694 million), or 74 cents per share, in the third quarter ended Sept. 28 from $619 million, or 50 cents per share, a year earlier.Net sales fell nearly 5% to $6.08 billion, missing analysts' estimates of $6.12 billion,..