Bug: [CI] Update NMI postman collection



Existing NMI postman collection is outdated and needs to be updated to the latest one look after regressions
## Type of Change
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- [ ] Bugfix
- [ ] New feature
- [ ] Enhancement
- [x] Refactoring
- [ ] Dependency updates
- [ ] Documentation
- [x] CI/CD

## Description
<!-- Describe your changes in detail -->
This PR aims at refactoring NMI collection by bringing it back to life. Added more flows to look after regressions.

Closes #3734

### 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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2. `crates/router/src/configs`
3. `loadtest/config`
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## Motivation and Context
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Why is this change required? What problem does it solve?
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We need to check for regressions.

## How did you test it?
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Did you write an integration/unit/API test to verify the code changes?
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Ran the collection:

<img width="980" alt="image" src="https://github.com/juspay/hyperswitch/assets/69745008/9aaad0eb-a4d7-4735-9d8c-303d323fc915">

There is a bug in NMI connector which needs to be addressed.  

Created a separate collection to reproduce it.

## Checklist
<!-- Put an `x` in the boxes that apply -->

- [ ] I formatted the code `cargo +nightly fmt --all`
- [ ] 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
