MiniMap多个组件渲染在界面上的时候会全部到最下面那个graphin组件里

**Describe the bug**

我自己封装了一个graphin组件，在里面使用了MiniMap组件，因为要渲染多个图，当时当多个图形都成功渲染，而且自己附加的画布操作等全部正常的时候，MiniMap组件却全部渲染到了最下面的组件中

**To Reproduce**

https://codesandbox.io/s/graphin-minimap-bug-1hj0f

**Expected behavior**

希望可以解决一下这种位置错误的问题，虽然渲染的图行是正确的

**Desktop (please complete the following information):**
- OS:windows10 21h2
- Browser:microsoft edge(based Chromium)
- Version:@antv/graphin@latest 2.2.1,@antv/graphin-components@latest 2.2.1

**Additional context**
Add any other context about the problem here.
目前如果要渲染多个minimap，只能通过导入G6的minimap，并使用当前gragpinRef的graph.addPlugin手动添加组件并设置样式解决

Start with the linked CodeSandbox and reproduce the layout with multiple Graphin components using MiniMap. Compare MiniMap rendering with the reported graphinRef plus G6 graph.addPlugin workaround; done means each MiniMap is positioned inside its own graph component rather than appearing in the last one.

Written by the indexing model from the issue text.