#7797799 WooExpress Trial: Update individual plugins page CTA and upgrade callout

Proposed Changes

• Update the button copy and action when installing a plugin that requires a plan upgrade while viewing the page from a site on the eCommerce Trial
• The CTA copy should say “Upgrade your plan” since we’re pointing folks toward the Plans page rather than directly to checkout, and therefore won’t automatically activate the given plugin for them after upgrading (unless there’s a way to do so I’m unaware of)
• Point to the Plans page with the plugins feature highlighted rather than directly to checkout for eCommerce Trials
• Update the upgrade copy to say “Included with eCommerce plans” since (in theory) users will have multiple plans to choose from
• Once we’ve agreed on the correct copy we need to add the String Freeze label to get new strings translated.

Before

After

Marketplace plugins

Minor copy update to these screens to reduce wordiness.

Testing Instructions

• Switch to this PR
• Create a new eCommerce Trial site from /setup/wooexpress
• Go to /plugins/[siteSlug] (you may need to do this manually in your browser because the Plugins screen gets taken off the menu for eCommerce Trial sites)
• Visit a non-marketplace plugin page (like Contact Form 7)
• The plans copy underneath the CTA should read “Included with eCommerce plans:” and list the same features as are currently listed for Business sites on this same page
• The CTA should read “Upgrade your plan”, and clicking it should take you to /plans/[siteSlug]?feature=install-plugins
• Switch to multiple sites on each different plan (Free, Premium, Business, eCommerce) to confirm they behave as they currently do in production with this PR

Pre-merge Checklist

• Has the general commit checklist been followed? (PCYsg-hS-p2)
• NA 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?
• NA 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)?
• NA 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)?

Related to #71853