feat(ja): reflect translation of core.json

[rdlabo]

Describe Problem

The translation/jp branch also translates core.json, and the preview screen shows the translated version. But https://ionicframework.com/docs/ja/ shows untranslated ones.

Describe Preferred Solution

In plugins/docusaurus-plugin-ionic-component-api/index.js , changes in translation/jp should be reflected when displayed at https://ionicframework.com/docs/ja/.

main branch:
https://github.com/ionic-team/ionic-docs/blob/main/plugins/docusaurus-plugin-ionic-component-api/index.js#L22

translation/jp branch
https://github.com/ionic-team/ionic-docs/blob/translation/jp/plugins/docusaurus-plugin-ionic-component-api/index.js#L23

Describe Alternatives

No response

Additional Information

No response