[WIP] i18n: Update Simplified Chinese translations (#7576)
* i18n: (zh-CN) #7027
* Rewording
This placeholder is also seen on single user page at Moderation > Accounts, where "this report" doesn't make sense.
* i18n: (zh-CN) #6425
* i18n: (zh-CN) #6497
* i18n: (zh-CN) #6246
* i18n: (zh-CN) Improvements