Doesn't have remove evict leader scheduler task in rolling_update.yml

[XSHui]

滚动升级 TiKV 节点（只升级 TiKV 服务）

Copy
ansible-playbook rolling_update.yml --tags=tikv

滚动升级 TiKV 实例时，Ansible 会迁移 region leader 到其他节点。具体逻辑为：调用 PD API 添加 

evict leader scheduler，每 10 秒探测一次该 TiKV 实例 leader_count， 等待 leader_count 降到 1 

以下或探测超 18 次后，即三分钟超时后，开始关闭 TiKV 升级，启动成功后再去除 evict leader

scheduler，串行操作。

The doc means stop tikv node if leader_count < 1 or check_time > 3min. Do remove evict leader scheduler after new tikv node has been started. But there doesn't have this task in rolling_update.yml

[liubo0127]

https://github.com/pingcap/tidb-ansible/blob/master/rolling_update.yml#L384