存在combo时，edge图层为什么会在node之上呢 #4738

Describe the bug

graph配置中开启linkCenter 在有combo的情况下，edge线条的图层在node节点（节点不在combo中）之下 而没有combo的情况下，edge线条的的图层却在node节点（节点不在combo中）之上 按教程中Group处说的，https://antv-g6.gitee.io/zh/docs/manual/middle/elements/shape/graphics-group nodeGroup图层应该保持比edgeGroup图层更高才对

Your Example Website or App

https://g6.antv.antgroup.com/examples/item/defaultCombos/#rect

Steps to Reproduce the Bug or Issue

import G6 from '@antv/g6';

const data = { nodes: [ { id: 'node1', size: 40, }, { id: 'node2', size: 40, }, ], combos: [ { id: 'combo', label: 'Combo', }, ], edges: [ { source: 'node1', target: 'node2', }, ] };

const width = document.getElementById('container').scrollWidth; const height = document.getElementById('container').scrollHeight || 500; const graph = new G6.Graph({ container: 'container', width, height, fitCenter: true, groupByTypes: false, modes: { default: ['drag-canvas', 'drag-node', 'drag-combo'], }, linkCenter: true, });

graph.data(data); graph.render();

Expected behavior

Screenshots or Videos

No response

Platform

• OS: [e.g. macOS, Windows, Linux]
• Browser: [e.g. Chrome, Safari, Firefox]
• Version: [e.g. 91.1]

Additional context

No response