Fix/issue 3672 right frozen count

[biubiukam]

[中文版模板 / Chinese template]

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🔗 Related issue link

fix #3672

💡 Background and solution

When rightFrozenColCount is decreased through the setter and the table has no bottom frozen rows, the right bottom frozen column group does not exist. dealRightFrozen still tried to move that missing group and threw before updating the count.

This change skips right bottom corner movement when the bottom frozen group is absent, while preserving the existing path when bottom frozen rows exist. A regression test covers the row series number scenario from the issue.

📝 Changelog

Language	Changelog
🇺🇸 English	Fix an error when decreasing rightFrozenColCount dynamically.
🇨🇳 Chinese	修复动态减小 rightFrozenColCount 时报错的问题。

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• Doc is updated/provided or not needed
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• TypeScript definition is updated/provided or not needed
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