Automatic combined style map names are passed to ufo2ft with undesirable values

When using fontmake to instantiate a UFO from designspace with multilingual names, the instance style map family names include additional undesirable names that should not be included.

For example, if I include this Python code in ufo2ft:
```py
print(instance.localisedFamilyName)
print(instance.localisedStyleName)
print(instance.localisedStyleMapFamilyName)
print(instance.localisedStyleMapStyleName)
```
before https://github.com/googlefonts/ufo2ft/blob/9cda1f16f25d7941f0f8a82b5ae1788150bf18d1/Lib/ufo2ft/instantiator.py#L782.

Using this designspace:

```xml

Weight
字重






















械黑 GB VF





械黑 GB VF














械黑 GB
Thin





械黑 GB
Regular





械黑 GB
Bold

```

Running `fontmake -i Thin -o ufo -m test.designspace`, the output is follow:

```
INFO:fontmake.font_project:Loading 2 DesignSpace source UFOs
INFO:fontmake.font_project:Interpolating master UFOs from designspace
INFO:fontmake.font_project:Generating instance UFO for 'Thin'
{'zh': '械黑 GB'}
{'zh': 'Thin'}
{'en': 'Frex Sans GB VF Thin', 'zh': '械黑 GB VF Thin'} // <-- where do this come from???
{}
INFO:fontmake.font_project:Saving instances\FrexSansGB-Thin.uf
```

Pretty sure this isn't on ufo2ft as I've written this part and there is a test case testing this exact scenario.

Reproduce the issue with the supplied designspace and `fontmake -i Thin -o ufo -m test.designspace`, then inspect the name handling around `ufo2ft/instantiator.py` line 782. Compare the localized family and style-map names with the designspace instance data; done means the generated instance no longer includes the unwanted combined names.

Written by the indexing model from the issue text.