By Nishant Kumar HONG KONG (Reuters) - SAC Capital Advisors, run by hedge fund titan Steven A. Cohen, has lost seven staff in Hong Kong and relocated five others there to New York and London, according to regulatory filings and people familiar with the matter. The departures come at a challenging time for the firm, with investors in February submitting redemption notices to pull around $1.7 billion from the $15 billion fund following a U.S. insider trading probe. ...