Issue:
Bug: [REFACTOR] : [Bluesnap] Add connector_transaction_id as fallback for webhooks



### Bug Description

Currently we are only consuming `merchant_transaction_id` from the webhook body, this was done to tackle the timeouts issue, but seems like Bluesnap doesn't always includes this id, so we need to add `connector_transaction_id` as fallback for webhook body

### Expected Behavior

 add `connector_transaction_id` as fallback for webhook body, so that even if merchant_transaction_id is not present webhook can be processed

### Actual Behavior

Currently we are only consuming `merchant_transaction_id` from the webhook body, this was done to tackle the timeouts issue, but seems like Bluesnap doesn't always includes this id, so we need to add `connector_transaction_id` as fallback for webhook body

### Steps To Reproduce

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### Context For The Bug

_No response_

### Environment

Are you using hyperswitch hosted version? Yes/No
If yes, please provide the value of the `x-request-id` response header to help us debug your issue.

If not (or if building/running locally), please provide the following details:
1. Operating System or Linux distribution:
2. Rust version (output of `rustc --version`): ``
3. App version (output of `cargo r --features vergen -- --version`): ``


### Have you spent some time checking if this bug has been raised before?

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

### Have you read the Contributing Guidelines?

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

### Are you willing to submit a PR?

Yes, I am 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 -->
add connector_txn_id fallback for webhook

### 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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Following are the paths where you can find config files:
1. `config`
2. `crates/router/src/configs`
3. `loadtest/config`
-->


## 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).
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#3316 

## How did you test it?
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Did you write an integration/unit/API test to verify the code changes?
Or did you test this change manually (provide relevant screenshots)?
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Trigger webhooks from Bluesnap with and without `merchant_transaction_id` and receive outgoing webhooks from Hyperswitch

<img width="1424" alt="Screenshot 2024-01-10 at 7 13 24 PM" src="https://github.com/juspay/hyperswitch/assets/55536657/5a743336-f53a-421f-9d23-d0e75344232d">




## 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
- [ ] I added a [CHANGELOG](/CHANGELOG.md) entry if applicable


Testing:


Trigger webhooks from Bluesnap with and without `merchant_transaction_id` and receive outgoing webhooks from Hyperswitch

<img width="1424" alt="Screenshot 2024-01-10 at 7 13 24 PM" src="https://github.com/juspay/hyperswitch/assets/55536657/5a743336-f53a-421f-9d23-d0e75344232d">

Patch:
diff --git a/crates/router/src/connector/bluesnap.rs b/crates/router/src/connector/bluesnap.rs
index edcad00c983..e54d8320d0f 100644
--- a/crates/router/src/connector/bluesnap.rs
+++ b/crates/router/src/connector/bluesnap.rs
@@ -1043,11 +1043,19 @@ impl api::IncomingWebhook for Bluesnap {
             | bluesnap::BluesnapWebhookEvents::Charge
             | bluesnap::BluesnapWebhookEvents::Chargeback
             | bluesnap::BluesnapWebhookEvents::ChargebackStatusChanged => {
-                Ok(api_models::webhooks::ObjectReferenceId::PaymentId(
-                    api_models::payments::PaymentIdType::PaymentAttemptId(
-                        webhook_body.merchant_transaction_id,
-                    ),
-                ))
+                if webhook_body.merchant_transaction_id.is_empty() {
+                    Ok(api_models::webhooks::ObjectReferenceId::PaymentId(
+                        api_models::payments::PaymentIdType::ConnectorTransactionId(
+                            webhook_body.reference_number,
+                        ),
+                    ))
+                } else {
+                    Ok(api_models::webhooks::ObjectReferenceId::PaymentId(
+                        api_models::payments::PaymentIdType::PaymentAttemptId(
+                            webhook_body.merchant_transaction_id,
+                        ),
+                    ))
+                }
             }
             bluesnap::BluesnapWebhookEvents::Refund => {
                 Ok(api_models::webhooks::ObjectReferenceId::RefundId(