sentinel cluster 的token server 是单点的吗？| Token Server HA and data syncing

## Issue Description

我大概看了下token server里面是个map来存统计数据，那token server 不会是单点得吧？如果是多个token server，那之间数据是怎么同步得呢？没看到文档里写，代码里好像没有？

### Describe what happened (or what feature you want)

### Describe what you expected to happen

### How to reproduce it (as minimally and precisely as possible)

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### Tell us your environment

### Anything else we need to know?

Start by reviewing the token server code that stores statistics in a map, then compare it with the existing documentation for deployment and synchronization. The issue needs a decided description of token-server high availability and data-sync behavior before implementation scope and completion criteria can be established.

Written by the indexing model from the issue text.