[QA] Add Cypress coverage for Billing Descriptor on Payload connector

[HS-QUALIBOT]

Summary

Add Cypress test coverage for the Billing Descriptor feature on the Payload connector.

Background

The Payload connector supports billing descriptors (statement_descriptor with 32-char max), but had no existing Cypress automation coverage for this feature. This issue tracks adding automated test coverage.

Changes Made

• Extended cypress/e2e/spec/Payment/43-BillingDescriptor.cy.js to support Payload connector
• Added PaymentIntentWithBillingDescriptor and PaymentConfirmWithBillingDescriptor config keys to cypress/e2e/configs/Payment/Payload.js
• Added payload to CONNECTOR_LISTS.INCLUDE.BILLING_DESCRIPTOR in cypress/e2e/configs/Payment/Utils.js
• Added DELAY config to prevent duplicate transaction errors on Payload
• Fixed amount_received assertion to match default payment amount (6000)

Test Results

• Billing descriptor spec: 9/9 tests PASS
• Payload connector regression: 9/9 tests PASS (including prereqs)

Related

• Parent pipeline issue: QAA-483