@OnlyForTest
    void tryElectSelf() {
        this.writeLock.lock();
        // unlock in electSelf
        electSelf();
    }
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