[venus] Set upgrade height through environment variables / 通过环境变量来设置升级高度

### 链服务模块 / Chain Service Components

- [X] venus
- [ ] venus-auth
- [ ] venus-gateway
- [ ] venus-messager
- [ ] venus-miner
- [ ] 文档 / docs

### 订单服务模块 / Deal Service Components

- [ ] venus-market
- [ ] 文档 / docs

### 算力服务模块 / Storage Power Service Components

- [ ] venus-sector-manager
- [ ] venus-worker
- [ ] 文档 / docs

### 描述 / Description

只有可执行程序的时候，希望通过环境变量来设置升级高度，从而不需要修改代码重新编译