Issue:
Bug: [REFACTOR]: [Iatapay] Remove Default Case Handling



### :memo: Feature Description

- We utilize match statements to make pivotal decisions, such as generating requests based on the payment method type and managing responses received from the connector. 
- These conditions generally go hand in hand with enum variants. 
- Default case is used because a match statement needs to be exhaustive i.e. every variant needs to be covered. 
- So, if all the explicit cases are handled then default is used to handle the rest.
- Each connector have these match statements but many of them don’t provide reference to each variant in their default case, rather a `_` is put to handle all the other cases. 
- This approach carries a risk because developers may inadvertently overlook the need for explicit handling of the new cases.

### :hammer: Possible Implementation

- Instead of relying on a default match case `_`, developers should handle each and every variant explicitly. 
- By doing so, if there are any changes in the future, they can readily assess the impact of their modifications simply by compiling the code.
- You can check this PR for further reference https://github.com/juspay/hyperswitch/pull/1955

:bookmark: Note: All the changes needed should be contained within `hyperswitch/crates/router/src/connector/`


### :package: Have you spent some time checking if this feature request has been raised before?

- [X] I checked and didn't find a similar issue

### :package: Have you read the Contributing Guidelines?

- [X] I have read the [Contributing Guidelines](https://github.com/juspay/hyperswitch/blob/main/docs/CONTRIBUTING.md)

### :sparkles: Are you willing to submit a PR?


Pull request description:
## Type of Change
<!-- Put an `x` in the boxes that apply -->

- [ ] Bugfix
- [ ] New feature
- [ ] Enhancement
- [X] Refactoring
- [ ] Dependency updates
- [ ] Documentation
- [ ] CI/CD

## Description
<!-- Describe your changes in detail -->
- Fix issue https://github.com/juspay/hyperswitch/issues/2272
- Changes to be made : Remove default case handling
- Added all the ```ConnectorAuthType``` (which are not ```auth_type``` ) against the default case
- File **changed: transformers.rs** (crates/router/src/connector/iatapay/transformers.rs)

### Additional Changes

- [ ] This PR modifies the API contract
- [ ] This PR modifies the database schema
- [ ] This PR modifies application configuration/environment variables

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1. `config`
2. `crates/router/src/configs`
3. `loadtest/config`
-->


## Motivation and Context
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## How did you test it?
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## Checklist
<!-- Put an `x` in the boxes that apply -->

- [ ] I formatted the code `cargo +nightly fmt --all`
- [ ] I addressed lints thrown by `cargo clippy`
- [ ] I reviewed the submitted code
- [ ] I added unit tests for my changes where possible
- [ ] I added a [CHANGELOG](/CHANGELOG.md) entry if applicable


Testing:

Patch:
diff --git a/crates/router/src/connector/iatapay/transformers.rs b/crates/router/src/connector/iatapay/transformers.rs
index 9d4ecdff197..f98798fe5be 100644
--- a/crates/router/src/connector/iatapay/transformers.rs
+++ b/crates/router/src/connector/iatapay/transformers.rs
@@ -86,7 +86,18 @@ impl TryFrom<&types::PaymentsAuthorizeRouterData> for IatapayPaymentsRequest {
         let payment_method = item.payment_method;
         let country = match payment_method {
             PaymentMethod::Upi => "IN".to_string(),
-            _ => item.get_billing_country()?.to_string(),
+
+            PaymentMethod::Card
+            | PaymentMethod::CardRedirect
+            | PaymentMethod::PayLater
+            | PaymentMethod::Wallet
+            | PaymentMethod::BankRedirect
+            | PaymentMethod::BankTransfer
+            | PaymentMethod::Crypto
+            | PaymentMethod::BankDebit
+            | PaymentMethod::Reward
+            | PaymentMethod::Voucher
+            | PaymentMethod::GiftCard => item.get_billing_country()?.to_string(),
         };
         let return_url = item.get_return_url()?;
         let payer_info = match item.request.payment_method_data.clone() {