It’s been a tumultuous few years for the packaged food industry, particularly for Chicago-area companies. Chicago-based Conagra Brands, known for Healthy Choice frozen meals and Slim Jim meat sticks, warned shareholders Wednesday that the company’s financials would get worse before it got better.Conagara CEO John Brase, who stepped into his role in June, said during the earnings call that a lack of investment into its portfolio was a problem and…