fix(billing): Check self serve partner value in hasBillingInfo (#104066)

closes
https://linear.app/getsentry/issue/BIL-1823/user-unable-to-upgrade-due-to-vercel-plan-issues

Author: brendanhsentry

static/gsApp/views/amCheckout/components/cart.spec.tsx

@@ -457,6 +457,7 @@ describe('Cart', () => {
         },
         name: 'partner',
       },
+      paymentSource: null,
     });
 
     render(
@@ -471,7 +472,9 @@ describe('Cart', () => {
     );
 
     // wait for preview to be loaded
-    await screen.findByRole('button', {name: 'Confirm and pay'});
+    await waitFor(() =>
+      expect(screen.getByRole('button', {name: 'Confirm and pay'})).toBeEnabled()
+    );
     screen.getByText(/you will be billed by Partner/);
   });
 

static/gsApp/views/amCheckout/utils.tsx

@@ -899,6 +899,10 @@ export function hasBillingInfo(
   subscription: Subscription,
   isComplete: boolean
 ) {
+  if (subscription.isSelfServePartner) {
+    return true;
+  }
+
   if (isComplete) {
     return !!subscription.paymentSource && hasSomeBillingDetails(billingDetails);
   }