Update Chinese address format

[ghost]

We have addr:district that works similar as addr:unit (in western style).
In Chinese language, the word 'unit' is translated to "单元"(a numbered entrance of a building), which is more specific than addr:housenumber, so there's no need to keep it.

See https://en.wikipedia.org/wiki/Address_(geography)#China

#3980
#4235

[JamesKingdom]

Thanks for changing this, it looks like unit is only used a few times in China.
I have never seen a Chinese address, so it is nice to hear recommendations from somebody with experience.
Look good 👍