private void stopStepDownTimer() {
        if (this.stepDownTimer != null) {
            this.stepDownTimer.stop();
        }
    }
Get max priority value for all nodes in the same Raft group, and update current node's target priority value.

@param peerIds peer nodes in the same Raft group
jraft-core/src/main/java/com/alipay/sofa/jraft/core/NodeImpl.java