collab: Fully move `StripeBilling` over to using `StripeClient` (#31722)
This PR moves over the last method on `StripeBilling` to use the
`StripeClient` trait, allowing us to fully mock out Stripe behaviors for
`StripeBilling` in tests.
Release Notes:
- N/A
c7047d5f0aMarshall Bowers committed on 5/29/2025, 11:49:14 PM· committed by GitHubparent406d975