Issue:
Bug: bug(events): update the ApiEventsType for `PaymentsSessionResponse` to use payments flow



update the `ApiEventMetric` trait for this response to return `ApiEventsType::Payment { payment_id : String}` variant.
based on the payment id stored in its body

This would help for better structuring and help list this api call in the dashboard events as well

Pull request description:
## Type of Change
<!-- Put an `x` in the boxes that apply -->

- [x] Bugfix


## Description
<!-- Describe your changes in detail -->
Updated the `ApiEventMetric` trait to return `ApiEventsType::Payment { payment_id : String}` variant.
Fixes #5059 



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Provide links to the files with corresponding changes.

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1. `config`
2. `crates/router/src/configs`
3. `loadtest/config`
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## Checklist
<!-- Put an `x` in the boxes that apply -->

- [x] I formatted the code `cargo +nightly fmt --all`
- [x] I reviewed the submitted code



Testing:

Patch:
diff --git a/crates/api_models/src/events.rs b/crates/api_models/src/events.rs
index bed46f01f19..fd974a8b9e2 100644
--- a/crates/api_models/src/events.rs
+++ b/crates/api_models/src/events.rs
@@ -40,7 +40,6 @@ impl ApiEventMetric for TimeRange {}
 
 impl_misc_api_event_type!(
     PaymentMethodId,
-    PaymentsSessionResponse,
     PaymentMethodCreate,
     PaymentLinkInitiateRequest,
     RetrievePaymentLinkResponse,
diff --git a/crates/api_models/src/events/payment.rs b/crates/api_models/src/events/payment.rs
index 4ed4e006669..ad2e2546f37 100644
--- a/crates/api_models/src/events/payment.rs
+++ b/crates/api_models/src/events/payment.rs
@@ -16,7 +16,7 @@ use crate::{
         PaymentsExternalAuthenticationRequest, PaymentsExternalAuthenticationResponse,
         PaymentsIncrementalAuthorizationRequest, PaymentsManualUpdateRequest,
         PaymentsRejectRequest, PaymentsRequest, PaymentsResponse, PaymentsRetrieveRequest,
-        PaymentsStartRequest, RedirectionResponse,
+        PaymentsSessionResponse, PaymentsStartRequest, RedirectionResponse,
     },
 };
 impl ApiEventMetric for PaymentsRetrieveRequest {
@@ -248,3 +248,11 @@ impl ApiEventMetric for PaymentsManualUpdateRequest {
         })
     }
 }
+
+impl ApiEventMetric for PaymentsSessionResponse {
+    fn get_api_event_type(&self) -> Option<ApiEventsType> {
+        Some(ApiEventsType::Payment {
+            payment_id: self.payment_id.clone(),
+        })
+    }
+}