[EE] i18n: externalize strings from 'app/views/dashboard'

What does this MR do?

EE MR for https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/19691.

Does this MR meet the acceptance criteria?

• Conform to the code review guidelines
  • Has been reviewed by a Backend maintainer
• EE specific content should be in the top level /ee folder
• Conforms to the merge request performance guidelines
• Conforms to the style guides
• Conform to the database guides
• If you have multiple commits, please combine them into a few logically organized commits by squashing them
• Internationalization required/considered
• End-to-end tests pass (package-and-qa manual pipeline job)

What are the relevant issue numbers?

Part of gitlab-ce#47670.