Cannot change the display language by installing the language pack extension via cli

## OS/Web Information

- Web Browser: firefox/edge
- Local OS: windows10
- Remote OS: centos7
- Remote Architecture: amd64
- `code-server --version`: 4.0.1 735c6da829535969ff7193c79379299e4a1cb9bc

## Steps to Reproduce

1. download language extension (https://marketplace.visualstudio.com/items?itemName=MS-CEINTL.vscode-language-pack-zh-hans)
2. install it `code-server --install-extension MS-CEINTL.vscode-language-pack-zh-hans-1.63.3.vsix`
3. start code-server

## Expected

Display language changed to Chinese

## Actual

nothing happens, even if I enter `Configure Display Language` through the command panel, there is no Chinese option


If I install this language extension online, a prompt will pop up in the lower right corner of the browser, asking if I want to change the display language, but there is no prompt after installing the extension offline


## Logs

## Screenshot



## Notes

This issue can be reproduced in VS Code: Yes/No