i18n: Refactor calypso-products percentages to use `numberFormat` #17285377

Part of addressing Automattic/i18n-issues#949

Proposed Changes

Refactors calypso-products package to use numberFormat for percentage values.
Several cases that involve plan features, like transaction fees, and other translations where percentages are hardcoded in strings

Media

Transaction fees Before/After in AR:

Why are these changes being made?

Part of addressing Automattic/i18n-issues#949

Testing Instructions

For transaction fees:

• test between AR/EL/EN locales
• go to /start/plans and open comparison grid
• confirm “transition fees” render correctly as in media above

Pre-merge Checklist

• Has the general commit checklist been followed? (PCYsg-hS-p2)
• Have you written new tests for your changes?
• Have you tested the feature in Simple (P9HQHe-k8-p2), Atomic (P9HQHe-jW-p2), and self-hosted Jetpack sites (PCYsg-g6b-p2)?
• Have you checked for TypeScript, React or other console errors?
• Have you used memoizing on expensive computations? More info in Memoizing with create-selector and Using memoizing selectors and Our Approach to Data
• Have we added the “[Status] String Freeze” label as soon as any new strings were ready for translation (p4TIVU-5Jq-p2)?
  • For UI changes, have we tested the change in various languages (for example, ES, PT, FR, or DE)? The length of text and words vary significantly between languages.
• For changes affecting Jetpack: Have we added the “[Status] Needs Privacy Updates” label if this pull request changes what data or activity we track or use (p4TIVU-aUh-p2)?