Issue: `nmi` tests shows different error messages for the same request

Postman Tests for nmi behaves like the following while running `Flow Testcases/Variation Cases/Scenario9-Create a mandate payment`

## Creating a mandate payment for `nmi`
```curl
curl --location '{{baseUrl}}/payments' \
--header 'Content-Type: application/json' \
--header 'Accept: application/json' \
--header 'api-key: {{apiKey}}' \
--data-raw '{
    "amount": 47074,
    "currency": "USD",
    "confirm": true,
    "capture_method": "automatic",
    "capture_on": "2022-09-10T10:11:12Z",
    "amount_to_capture": 47074,
    "customer_id": "StripeCustomer",
    "email": "guest@example.com",
    "name": "John Doe",
    "phone": "999999999",
    "phone_country_code": "+65",
    "description": "Its my first payment request",
    "authentication_type": "no_three_ds",
    "return_url": "https://duck.com",
    "payment_method": "card",
    "payment_method_data": {
        "card": {
            "card_number": "4111111111111111",
            "card_exp_month": "10",
            "card_exp_year": "69",
            "card_holder_name": "joseph Doe",
            "card_cvc": "123"
        }
    },
    "setup_future_usage": "off_session",
    "mandate_data": {
        "customer_acceptance": {
            "acceptance_type": "offline",
            "accepted_at": "1963-05-03T04:07:52.723Z",
            "online": {
                "ip_address": "127.0.0.1",
                "user_agent": "amet irure esse"
            }
        },
        "mandate_type": {
            "single_use": {
                "amount": 7000,
                "currency": "USD"
            }
        }
    },
    "customer_acceptance": {
        "acceptance_type": "online",
        "accepted_at": "2022-09-10T10:11:12Z",
        "online": {
            "ip_address": "123.32.25.123",
            "user_agent": "Mozilla/5.0 (Linux; Android 12; SM-S906N Build/QP1A.190711.020; wv) AppleWebKit/537.36 (KHTML, like Gecko) Version/4.0 Chrome/80.0.3987.119 Mobile Safari/537.36"
        }
    },
    "billing": {
        "address": {
            "line1": "1467",
            "line2": "Harrison Street",
            "line3": "Harrison Street",
            "city": "San Fransico",
            "state": "California",
            "zip": "94122",
            "country": "US",
            "first_name": "John"
        }
    },
    "shipping": {
        "address": {
            "line1": "1467",
            "line2": "Harrison Street",
            "line3": "Harrison Street",
            "city": "San Fransico",
            "state": "California",
            "zip": "94122",
            "country": "US",
            "first_name": "John"
        }
    },
    "statement_descriptor_name": "joseph",
    "statement_descriptor_suffix": "JS",
    "metadata": {
        "udf1": "value1",
        "new_customer": "true",
        "login_date": "2019-09-10T10:11:12Z"
    }
}'
```
### Integ Response
```json
{
    "error": {
        "type": "invalid_request",
        "message": "Payment method type not supported",
        "code": "IR_19",
        "reason": "credit mandate payment is not supported by nmi"
    }
}
```
### SBX Response
```json
{
    "error": {
        "type": "invalid_request",
        "message": "Payment method type not supported",
        "code": "IR_19",
        "reason": "debit mandate payment is not supported by nmi"
    }
}
```

It shows different error messages for two environments.

Resolution: <think>
PR Context:
- Title: ci(postman): update assertion error message for nmi collection
- Merged: 2025-04-17T07:51:28Z
- Files changed: 2 files
- Commits: 10 commits

Implementation approach:
## Type of Change
<!-- Put an `x` in the boxes that apply -->

- [ ] Bugfix
- [ ] New feature
- [ ] Enhancement
- [x] Refactoring
- [ ] Dependency updates
- [ ] Documentation
- [x] CI/CD

## Description
<!-- Describe your changes in detail -->
Postman Tests for `nmi` were failing on SBX (but not on Integ) because `Flow Testcases/Variation Cases/Scenario9-Create a mandate payment` responded an error message as `debit mandate payment is not supported by nmi` on SBX and `credit mandate
</think>

To implement this, you'll need to modify:


(No detailed commit information available)