Issue:
Bug: Required fields absent in PML in case of Gift Card for OnSession (v2)



In case of `Adyen` connector and `Givex` payment method subtype, required fields are absent in PML output when `setup_future_usage` is `OnSession`

Need to move givex required fields to common in the required fields TOML

Pull request description:
## Type of Change
<!-- Put an `x` in the boxes that apply -->

- [x] Bugfix
- [ ] New feature
- [ ] Enhancement
- [ ] Refactoring
- [ ] Dependency updates
- [ ] Documentation
- [ ] CI/CD

## Description
<!-- Describe your changes in detail -->
- Moved required fields for `givex` gift card for `Adyen` from `non-mandate` to `common`

### Additional Changes

- [ ] This PR modifies the API contract
- [ ] This PR modifies the database schema
- [ ] This PR modifies application configuration/environment variables

<!--
Provide links to the files with corresponding changes.

Following are the paths where you can find config files:
1. `config`
2. `crates/router/src/configs`
3. `loadtest/config`
-->

config/payment_required_fields_v2.toml

## Motivation and Context
<!--
Why is this change required? What problem does it solve?
If it fixes an open issue, please link to the issue here.

If you don't have an issue, we'd recommend starting with one first so the PR
can focus on the implementation (unless it is an obvious bug or documentation fix
that will have little conversation).
-->
Closes #9413 

## How did you test it?
<!--
Did you write an integration/unit/API test to verify the code changes?
Or did you test this change manually (provide relevant screenshots)?
-->

- PML Request:

```
curl --location 'http://localhost:8080/v2/payments/12345_pay_019956cafc887e028748d3bf29b35a2e/payment-methods' \
--header 'Content-Type: application/json' \
--header 'x-profile-id: pro_DsAY3PdGJ0ROvUdK6EpX' \
--header 'Authorization: publishable-key=pk_dev_304de2a7a06e4074967faa195a48bd4a, client-secret=cs_019956cafc967983b4b673f259b6680e' \
--header 'api-key: pk_dev_304de2a7a06e4074967faa195a48bd4a'
```

- PML Response:

```json
{
    "payment_methods_enabled": [
        {
            "payment_method_type": "card",
            "payment_method_subtype": "card",
            "payment_experience": null,
            "required_fields": [],
            "surcharge_details": null
        },
        {
            "payment_method_type": "card_redirect",
            "payment_method_subtype": "card_redirect",
            "payment_experience": [
                "redirect_to_url"
            ],
            "required_fields": [],
            "surcharge_details": null
        },
        {
            "payment_method_type": "pay_later",
            "payment_method_subtype": "klarna",
            "payment_experience": [
                "redirect_to_url"
            ],
            "required_fields": [],
            "surcharge_details": null
        },
        {
            "payment_method_type": "wallet",
            "payment_method_subtype": "apple_pay",
            "payment_experience": null,
            "required_fields": [],
            "surcharge_details": null
        },
        {
            "payment_method_type": "wallet",
            "payment_method_subtype": "google_pay",
            "payment_experience": null,
            "required_fields": [],
            "surcharge_details": null
        },
        {
            "payment_method_type": "wallet",
            "payment_method_subtype": "paypal",
            "payment_experience": null,
            "required_fields": [
                {
                    "required_field": "payment_method_data.billing.email",
                    "display_name": "email_address",
                    "field_type": "user_email_address",
                    "value": null
                }
            ],
            "surcharge_details": null
        },
        {
            "payment_method_type": "gift_card",
            "payment_method_subtype": "givex",
            "payment_experience": null,
            "required_fields": [
                {
                    "required_field": "payment_method_data.gift_card.givex.number",
                    "display_name": "gift_card_number",
                    "field_type": "user_card_number",
                    "value": null
                },
                {
                    "required_field": "payment_method_data.gift_card.givex.cvc",
                    "display_name": "gift_card_cvc",
                    "field_type": "user_card_cvc",
                    "value": null
                }
            ],
            "surcharge_details": null
        }
    ],
    "customer_payment_methods": []
}
```
## Checklist
<!-- Put an `x` in the boxes that apply -->

- [x] I formatted the code `cargo +nightly fmt --all`
- [x] I addressed lints thrown by `cargo clippy`
- [x] I reviewed the submitted code
- [ ] I added unit tests for my changes where possible


Testing:


- PML Request:

```
curl --location 'http://localhost:8080/v2/payments/12345_pay_019956cafc887e028748d3bf29b35a2e/payment-methods' \
--header 'Content-Type: application/json' \
--header 'x-profile-id: pro_DsAY3PdGJ0ROvUdK6EpX' \
--header 'Authorization: publishable-key=pk_dev_304de2a7a06e4074967faa195a48bd4a, client-secret=cs_019956cafc967983b4b673f259b6680e' \
--header 'api-key: pk_dev_304de2a7a06e4074967faa195a48bd4a'
```

- PML Response:

```json
{
    "payment_methods_enabled": [
        {
            "payment_method_type": "card",
            "payment_method_subtype": "card",
            "payment_experience": null,
            "required_fields": [],
            "surcharge_details": null
        },
        {
            "payment_method_type": "card_redirect",
            "payment_method_subtype": "card_redirect",
            "payment_experience": [
                "redirect_to_url"
            ],
            "required_fields": [],
            "surcharge_details": null
        },
        {
            "payment_method_type": "pay_later",
            "payment_method_subtype": "klarna",
            "payment_experience": [
                "redirect_to_url"
            ],
            "required_fields": [],
            "surcharge_details": null
        },
        {
            "payment_method_type": "wallet",
            "payment_method_subtype": "apple_pay",
            "payment_experience": null,
            "required_fields": [],
            "surcharge_details": null
        },
        {
            "payment_method_type": "wallet",
            "payment_method_subtype": "google_pay",
            "payment_experience": null,
            "required_fields": [],
            "surcharge_details": null
        },
        {
            "payment_method_type": "wallet",
            "payment_method_subtype": "paypal",
            "payment_experience": null,
            "required_fields": [
                {
                    "required_field": "payment_method_data.billing.email",
                    "display_name": "email_address",
                    "field_type": "user_email_address",
                    "value": null
                }
            ],
            "surcharge_details": null
        },
        {
            "payment_method_type": "gift_card",
            "payment_method_subtype": "givex",
            "payment_experience": null,
            "required_fields": [
                {
                    "required_field": "payment_method_data.gift_card.givex.number",
                    "display_name": "gift_card_number",
                    "field_type": "user_card_number",
                    "value": null
                },
                {
                    "required_field": "payment_method_data.gift_card.givex.cvc",
                    "display_name": "gift_card_cvc",
                    "field_type": "user_card_cvc",
                    "value": null
                }
            ],
            "surcharge_details": null
        }
    ],
    "customer_payment_methods": []
}
```

Patch:
diff --git a/config/payment_required_fields_v2.toml b/config/payment_required_fields_v2.toml
index 299da49ee02..47de2192c3e 100644
--- a/config/payment_required_fields_v2.toml
+++ b/config/payment_required_fields_v2.toml
@@ -2331,12 +2331,12 @@ non_mandate = []
 
 # Payment method type: Givex
 [required_fields.gift_card.givex.fields.Adyen]
-common = []
-mandate = []
-non_mandate = [
+common = [   
     { required_field = "payment_method_data.gift_card.givex.number", display_name = "gift_card_number", field_type = "user_card_number" },
     { required_field = "payment_method_data.gift_card.givex.cvc", display_name = "gift_card_cvc", field_type = "user_card_cvc" }
 ]
+mandate = []
+non_mandate = []
 
 # CardRedirect (Assuming this section might be missing or problematic, so placing MobilePayment after GiftCard)
 # If CardRedirect exists and is correct, MobilePayment should come after it.