Ensure all plans are refreshed for existing subscriptions (Admin Portal) | Fetch All Subscriptions

[c-whitehead]

Describe the bug
When clicking the "Fetch All Subscriptions" button, newly added plans to the published offer are not being retrieved for existing subscriptions. At the moment, a new subscription (i.e. subscribe to a new offer) has to be created to ensure its associated offer plans are also retrieved and shown in the Admin portal.

To Reproduce

1. In Partner Center, publish a new offer.
2. Subscribe to the offer.
3. In Admin portal, click the "Fetch All Subscriptions" button to retrieve the new subscription.
4. In Admin portal go to "Plans" to view the plans associated with the new subscription.
5. In Partner Center, add a new plan to the existing offer and re-publish.
6. In Admin portal, click the "Fetch All Subscriptions" button.
7. In Admin portal go to "Plans" - the newly added plan is not listed?

Expected behavior
In Admin portal, expect to see the newly added plan in the "Plans" section after refreshing all subscriptions.