Add test coverage for RabbitMQ publishing logic

[Mrigankkh]

Description
Ensure the notification logic has sufficient unit and integration test coverage. Mock RabbitMQ wherever appropriate.

Tasks

Mock RabbitTemplate in unit tests

Use assertions to verify message structure and publish call

Optional: set up integration test with Testcontainers or EmbeddedRabbit

Testing

All public methods should be covered

Validate proper error handling/logging if publish fails