LONDON — Britain's most senior civil servant is negotiating his exit from government as Keir Starmer battles to steady his crisis-hit government. Chris Wormald is expected to resign as cabinet secretary after just over a year in post, according to three U.K. officials, granted anonymity to talk about internal discussions. The announcement could come Tuesday, although the officials stressed the timing is still to be decided. Wormald will be the third senior figure to leave Starmer's Downing