Updating Chinese (Simplified) translations (#5508)

* i18n: (zh-CN) fix punctuations and spaces
Spaces are fixed according to https://github.com/sparanoid/chinese-copywriting-guidelines

* i18n: (zh-CN) fix punctuation

* i18n: (zh-CN) Adapt official translation of Discourse Privacy Policy from GitHub, with minor fixes
https://github.com/discourse/discourse/blob/master/config/locales/server.zh_CN.yml#L2677

* i18n: (zh-CN) Update missing translations

* i18n: (zh-CN) Fixing errors

* i18n: (zh-CN) Fix indent error

* i18n: (zh-CN) Fix language tag

* i18n: (zh-CN) Remove quotes

* i18n: (zh-CN) Update translation (#5485)

* i18n: (zh-CN) Remove whitespaces, x -> ×

* i18n: (zh-CN) Rewording on time distance

* i18n: (zh-CN) Overall improvements

* i18n: (zh-CN) i18n-tasks normalization

* i18n: (zh-CN) Add missing translation