#8028803 Pricing Grid: Fixes billing timeframe for 2Y & 3Y plans

Fixes Automattic/martech#1811

Proposed Changes

Note: Once the PR is approved, I’ll add the String Freeze label to send the new text for translations.

• Fixes the billing timeframe for 2Y and 3Y plans. The billing timeframe refers to the text below the price in the pricing grid.
• Screenshots:

2Y plans:

Before	After

3Y plans:

Before	After

Testing Instructions

• The unit tests should cover all possible cases.
• On a site with a 2Y plan, go to /plans and confirm that the text matches the screenshot.
• On a site with a 3Y plan, go to /plans and confirm that the text matches the screenshot.

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 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-ajp-p2)?