Pause legacy Stripe Billing subscriptions on WooPayments 9.3 upgrade

[mattallan]

Project Thread: pgizk6-42-p2
Related Epic: #10401

This issue is being handled by the Chronos team as part of our Subscriptions Primary Offering project, as such, I've added this to our team's project board.

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• Targeted release: WooPayments 9.3

Background

There are a small number of US merchants using a legacy implementation of our Stripe Billing subscriptions feature without the WooCommerce Subscriptions extension. Back in 2023, we attempted to move merchants away from this, however that was not 100% successful.

This issue is part 4 of 5 where the goal is to migrate these merchants off using deprecated Subscriptions code bundled in WooPayments which is soon to be removed, over to installing the WooCommerce Subscriptions extension to continue selling subscription products.

This issue comes one release before the woocommerce/subscriptions-core composer package is scheduled to be removed, before this, we want to ensure all existing legacy Stripe Billing subscriptions are paused so they don't keep renewing once it's no longer supported.

Acceptance Criteria

Important

These changes should only impact US merchants that have active Stripe Billing subscriptions but don't have the WooCommerce Subscriptions extension installed.

• Upon upgrading to WooPayments 9.3, run a script that finds any active legacy Stripe Billing subscriptions and sets them to on-hold.
• Update the text in the Admin Notice and WooCommerce Admin note to explain to merchants why some of their subscriptions are on-hold and how to fix this (i.e by installing WooCommerce Subscriptions)
• While the store does not have WooCommerce Subscriptions installed, prevent merchants from reactivating these legacy subscriptions