Add gitlab duo translations

Step 1: What is changing in this MR?

• Adds content in /de-de/ /fr-fr/ /ja-jp/ content folders for translated /gitlab-duo.json
• Removes Contentful implementation of old translated content

Production	Review app
https://about.gitlab.com/gitlab-duo	https://3707-gitlab-duo-new-translations-json-data-in-be.about.gitlab-review.app/gitlab-duo/
https://about.gitlab.com/gitlab-duo/fr-fr/	https://3707-gitlab-duo-new-translations-json-data-in-be.about.gitlab-review.app/fr-fr/gitlab-duo/
https://about.gitlab.com/gitlab-duo/de-de/	https://3707-gitlab-duo-new-translations-json-data-in-be.about.gitlab-review.app/de-de/gitlab-duo
https://about.gitlab.com/gitlab-duo/ja-jp/	https://3707-gitlab-duo-new-translations-json-data-in-be.about.gitlab-review.app/ja-jp/gitlab-duo/

Step 2: Ensure that your changes comply with the following, where applicable:

• I, the Assignee, have run Axe tools on any updated pages, and fixed the relevant accessibility issues.
• These changes work on both Safari, Chrome, and Firefox.
• These changes have been reviewed for Visual Quality Assurance and Functional Quality Assurance on Mobile, Desktop, and Tablet.
• These changes work with our Google Analytics and SEO tools.
• These changes have been documented as expected.

Step 3: Ensure that your changes don't cause regressions on key pages, where applicable:

Production	Review app
https://about.gitlab.com/	WIP
https://about.gitlab.com/ja-jp/	WIP
https://about.gitlab.com/pricing/	WIP
https://about.gitlab.com/ja-jp/pricing/	WIP
https://about.gitlab.com/sales/	WIP
https://about.gitlab.com/gitlab-duo/	WIP
https://about.gitlab.com/enterprise/	WIP
https://about.gitlab.com/platform/	WIP
https://about.gitlab.com/free-trial/	WIP

Build Variables:

• Use Contentful Preview API

Closes #3707 (closed)