Update item titles and add help text in Geo nodes admin dashboard

What does this MR do?

This MR does following changes to Geo nodes admin dashboard;

• Adds help text as per https://gitlab.com/gitlab-org/gitlab-ee/issues/5146#copy-in-the-tooltips to items under verification section
• Removes colon (:) from the item title to match with the updated design.

Screenshots

Primary Node	Secondary Node

Does this MR meet the acceptance criteria?

• Changelog entry added, if necessary
• [ ] Documentation created/updated
• [ ] API support added
• Tests added for this feature/bug
• Review
  • Has been reviewed by UX
  • Has been reviewed by Frontend
  • [ ] Has been reviewed by Backend
  • [ ] Has been reviewed by Database
• Conform by the merge request performance guides
• Conform by the style guides
• Squashed related commits together
• Internationalization required/considered
• [ ] If paid feature, have we considered GitLab.com plan and how it works for groups and is there a design for promoting it to users who aren't on the correct plan
• [ ] End-to-end tests pass (package-qa manual pipeline job)

What are the relevant issue numbers?

Closes #5146 (closed)