Removes the gap in approvers in the MR widget

What does this MR do?

• Removes the gap from the Approvals in the MR widget

• Sets the same margin between all components of the approvals

• Aligns the "Remove your approval" button vertically: (the following images are not horizontally spaced correct)

before	after

• Simplifies the HTML of the component, rendering the same content:
• Adds missing keys in Vue props
• Fixes invalid HTML

Final result:

Does this MR meet the acceptance criteria?

• Changelog entry added, if necessary
• [ ] Documentation created/updated
• [ ] API support added
• Tests
  • [ ] Added for this feature/bug
  • All builds are passing
• Conform by the merge request performance guides
• Conform by the style guides
• Branch has no merge conflicts with master (if it does - rebase it please)
• Squashed related commits together

What are the relevant issue numbers?

Closes https://gitlab.com/gitlab-org/gitlab-ee/issues/3329