Remove references to sunset chinese website

[NotMyFault]

The chinese website remains almost unmodified since 2019 and there are ongoing efforts to detach it from our resources. I would like to remove it from the navbar component. Not only for the reason that it's in a sunset state, but also to draw focus on jenkins.io and prevent future misguidance of newbie contributors and GSoC students who want to contribute.

[jenkins-io-components[bot]]

:tada: This PR is included in version 1.18.0 :tada:

The release is available on:

• npm package (@latest dist-tag)
• GitHub release

Your semantic-release bot :package::rocket:

[halkeye]

cdn caches for 6 hours, so unlikey to see till tomororw, but code is live!