EE Port of 47008-issue-board-card-design

What does this MR do?

This MR updates the design of issue board cards.

Old Design	New Design

CE MR: https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/21229

What are the relevant issue numbers?

https://gitlab.com/gitlab-org/gitlab-ce/issues/47008

Does this MR meet the acceptance criteria?

• Changelog entry added, if necessary
• Documentation created/updated
• Tests added for this feature/bug
• Conforms to the code review guidelines
• Conforms to the merge request performance guidelines
• Conforms to the style guides
• Conforms to the database guides
• EE specific content should be in the top level /ee folder
• For a paid feature, have we considered GitLab.com plans, how it works for groups, and is there a design for promoting it to users who aren't on the correct plan?

Closes https://gitlab.com/gitlab-org/gitlab-ce/issues/47008