Don't allow renewal of inactive products

[gtandersen]

Describe the bug Products that are no longer active should not have a "Renew" button in Your Subscriptions.

To Reproduce Steps to reproduce the behavior:

1. Go to https://runbox.com/app/account/subscriptions
2. Observe the "Renew" button next to inactive products such as additional Email Storage Space
3. Click to renew the product
4. Click the shopping cart icon in the top right corner
5. Observe the error "Some of the products added to your cart (#1) are not currently available for purchase."

Expected behavior Inactive products should not have a "Renew" button next to them.

Screenshots

Desktop (please complete the following information):

• OS: macOS
• Browser: Firefox