#7608234 Update Gifting settings toggle texts

Proposed Changes

Following #69637 (comment), we need to updated the Gifting settings toggle text.

[Toggle] Allow a site visitor to gift site plan costs.
Allow a site visitor to cover the full cost of your site’s WordPress plan.

Testing Instructions

1. Using a site with Auto-Renew Off.
2. Go to /settings/general/[your-site]?flags=subscription-gifting.
3. Check the text and description of the Gifting Subscriptions section. (screenshot)

Screenshot

Pre-merge Checklist

• 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)?

Fixes Automattic/dotcom-forge#1154