SPRINGFIELD — Illinois has awarded a more than $4 billion prison medical care contract to the same company it’s used for three decades, despite multimillion-dollar lawsuits against the firm and statewide complaints alleging substandard care.Pittsburgh-based Wexford Health Sources was one of two companies responding to a request for proposals from the Illinois Department of Corrections, but it was not the low bidder. Wexford’s offer came in $673 million higher than one from VitalCore Health Strategies of …