[Bug] Multiple map series and visualMap objects not mapping as expected

### Version

5.5.1

### Link to Minimal Reproduction

https://codepen.io/amcveyCW/pen/OPLbpbd

### Steps to Reproduce

1. Add at least two `series` objects. Each should be of `type` 'map,' reference some map SVG, and include their own data array relating to the referenced map.
2. Create a matching number of `visualMap` objects, either 'piecewise' or 'continuous' `type`. Set up some unique min/max/color/etc for each object. Each should include `seriesIndex` and the value should reference one of the corresponding `series` object created in the above step.
3. Include `legend` for testing purposes.
4. Note that the first `visualMap` object's `seriesIndex` is not respected and it controls both map series. By comparison, the following `visualMap` objects behave correctly and their `seriesIndex` is respected. This is visible when the first map (A) is deselected from the legend.

### Current Behavior

The first `visualMap` object thresholds and colors are applied to all series objects. If `type` 'continuous' - the following `series` objects are mapped to the first visualMap's 'max' color. If `type` 'piecewise' - the following `series` objects are mapped to the first `visualMap` object's 'outofrange' color.

### Expected Behavior

Each `series` object to map to its corresponding `visualMap` object when referenced using the related `seriesIndex` and depict the threshold colors of that `visualMap` object.

### Environment

_No response_

### Any additional comments?

Both continuous and piecewise examples:
https://codepen.io/amcveyCW/pen/OPLbpbd
https://codepen.io/amcveyCW/pen/QwLGpdL

NOTE: One `visualMap` is not sufficient in my case where I have two separate regions that map to two different metrics. Imagine an image of a radiator and a fan - the radiator is mapped to a temperature value while the fan is mapped to a speed value.

NOTE: Using `geo` and `geoIndex` is an alternative that does not cause superimposed maps. https://codepen.io/amcveyCW/pen/MYgJxaV