Donna B. Coaxum’s legal department spends most of its time helping finalize deals that sell beans and salsa to burrito joints, sausage and pepperoni to sandwich shops and chicken to fast-food restaurants. You’ve probably eaten her company’s products, but you might never have heard of OSI Group LLC, the Aurora-based food services provider that operates in 17 countries and does business with some of the largest restaurants in the world. “We’re everywhere, doing a lot of stuff,” said …