UK Stocks-Factors to watch on May 31

May 31 (Reuters) - Britain's FTSE 100 index is seen opening up 8 points at 7535 on Wednesday, according to financial bookmakers. * INDIVIOR: British drugmaker Indivior Plc said on Tuesday it applied for a new drug application to the U.S. Food and Drug Administration to market its drug to treat opioid use disorder (OUD). * ANTOFAGASTA: Chilean mining company Antofagasta Minerals has sold its minority stake in a solar park in northern Chile, and will launch a power auction for on