The U.S. judge overseeing an auction of shares in a Citgo Petroleum parent to pay Venezuela-linked creditors on Wednesday proposed major procedural changes to advance a case stalled by wide opposition and lawsuits by creditors in other courts.Judge Leonard Stark recommended a series of changes to encourage higher bids in a seven-year-long court case brought by companies pursuing up to $21.3 billion in claims for debt defaults and expropriations in Venezuela…