cleanupOrphaned has duplicated writeConcern

cleanupOrphaned currently takes a writeConcern and a secondaryThrottle parameter. Since we're now waiting for writeConcern in the central Command::run(), this command is already waiting for writeConcern at the end. This writeConcern value is not, however, modified by the secondaryThrottle parameter like it is in cleanupOrphaned. cleanupOrphaned, when initiated by a user, thus now waits for writeConcern an extra time at the end. If we remove throttling we should also clean up the secondaryThrottle and writeConcern code.