docs(input-number): only group the integer part in formatter demo

[lazerg]

The formatter demo applies the thousands separator regex to the whole number, so the decimal part gets commas as well. 1.0445 renders as $ 1.0,445.

Split the value on the decimal point and group only the integer part, the way the antd demo and Statistic already do.

Fixes #8576

Change Log

Language	Changelog
🇺🇸 English	Fix the InputNumber formatter demo inserting separators inside the decimal part.
🇨🇳 Chinese	修复 InputNumber 格式化演示中小数部分被插入千分位分隔符的问题。