Send Merchant Account Id to PaymentMethod Create

[yeseniamolinab]

Overview

During the QA of 3DS, we encountered an error when trying to make a monthly donation. The error we are getting back from BT is:

Merchant account must match the 3D Secure authorization merchant account. (94284 on merchant_account_id)

The error happens when we call the transaction endpoint in Champaign; however, the issue is actually happening when we call the create method ::Braintree::PaymentMethod.create(payment_method_options) because we are not sending the merchant account id information; therefore, Braintree uses the default.

The issue is affecting both, Champaign and Pronto.

Ticket

https://app.asana.com/0/1119304937718815/1201335394700376/f

[yeseniamolinab]

@osahyoun @subbiahf22 merging this to resume 3DS testing ASAP and getting a production deployment on Monday.
Please let me know any feedback you might have, and I will address it tomorrow in a follow-up PR.

Thanks!