The list of luminaries shunning a Saudi Arabia investment conference expanded Thursday, with Goldman Sachs Group Inc. and Treasury Secretary Steven Mnuchin canceling while Fox Business pulled out as a media partner... “This incident is unacceptable and clearly they have to answer questions,” Goldman Sachs CEO David Solomon said Thursday in a CNBC interview. Saudi leaders’ response to the international uproar “will have an impact on how we all interact,” said Solomon...