Add BDD test for event subscription

### Description

Related to #3621

It probably worth it to add a BDD test for event subscription. I believe it's something all BDD test should implement.

### Affected area / component

bdd test/CI

### Proposed solution

Add a `event_subscription.feature` file and implement it.

### Alternatives considered

N/A

### Contribution

- [x] I'm willing to submit a pull request to implement this feature

### Good first issue

- [x] I think this could be a good first issue for a new contributor