缺失面积图 tooltip 颜色获得有误 #4926

• 链接：https://g2.antv.antgroup.com/examples/general/area/#missing-data-area
• 版本：5.0.4

<img src="https://user-images.githubusercontent.com/49330279/235040579-f72b26bd-2886-4639-aa3f-68f544060b61.png" width=640 />