Setup Stripe discount coupon for preview teams

[jankeromnes]

[jankeromnes]

The coupon has been created and is ready for use. ✅

Until #12341 is implemented though, this coupon needs to be applied manually by a Stripe admin to an existing Stripe subscription (i.e. after a customer has subscribed to usage-based by adding a valid payment method). I'm happy to help with this -- please simply ping me when needed.