Resolve "Monitoring graphs - Popover value improvements" - EE

What does this MR do?

This is the EE counterpart for: https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/18353

Screenshots (if relevant)

Does this MR meet the acceptance criteria?

• Changelog entry added, if necessary
• Tests added for this feature/bug
• Review
  • Has been reviewed by UX
  • Has been reviewed by Frontend
• Conform by the merge request performance guides
• Conform by the style guides
• Squashed related commits together

What are the relevant issue numbers?

https://gitlab.com/gitlab-org/gitlab-ce/issues/41783 closes: https://gitlab.com/gitlab-org/gitlab-ee/issues/5573