Reduce Liquid logic on china community page (#12547)

This PR keeps the contents of the page mostly the same but reduces the
use of complicated Liquid templating and includes. This does result in a
little bit more duplication, but will be easier to maintain and keep
compatible with future site infrastructure.

**Staged:**
https://flutter-docs-prod--pr12547-misc-simplify-use-in-china-redp7hxp.web.app/community/china

Author: parlough