chore: Translate transifex_input.json in zh_CN

96% of minimum 50% translated source file: 'transifex_input.json'
on 'zh_CN'.

Sync of partially translated files: 
untranslated content is included with an empty translation 
or source language content depending on file format

translations/frontend-app-account/src/i18n/messages/zh_CN.json

@@ -255,6 +255,7 @@
   "notification.preference.heading": "通知",
   "notification.preference.app.title": "{ key, select, discussion {Discussions} coursework {Course Work} other {{key}} }",
   "notification.preference.title": "{ text, select, core {Core notifications} newDiscussionPost {New discussion posts} newQuestionPost {New question posts} contentReported {Reported content} other {{text}} }",
+  "notification.preference.channel": "{ text, select, web {Web} email {Email} push {Push} other {{text}} }",
   "notification.preference.type.label": "类型",
   "notification.preference.web.label": "网页",
   "notification.preference.help.email": "邮箱",