Remove unused CSS selectors for Cycle Analytics (between 1st iteration and 2nd iteration)

What does this MR do?

Removes unused CSS selectors for Cycle Analytics (between 1st iteration and 2nd iteration).

Are there points in the code the reviewer needs to double check?

No.

Why was this MR needed?

Unused CSS code should be removed to reduce bugs and to improve server-/client-side performance.

Screenshots (if relevant)

n/a

Does this MR meet the acceptance criteria?

• Changelog entry added, if necessary
• [n/a] Documentation created/updated
• [n/a] API support added
• [n/a] Tests added for this feature/bug
• Review
  • Has been reviewed by UX
  • Has been reviewed by Frontend
  • [n/a] Has been reviewed by Backend
  • [n/a] Has been reviewed by Database
• Conform by the merge request performance guides
• Conform by the style guides
• Squashed related commits together
• [n/a] Internationalization required/considered

What are the relevant issue numbers?

Closes #41743 (closed)

Part of #39584 (moved)