RHCLOUD-43290 needs to be tested in IQE.

So far, there are two scenarios:

• Events from subscription-services (bundle) / subscriptions (application) are deduplicated using a deduplication key specific to SubWatch (see notifications-backend#3826).
• Events from all other tenants are deduplicated with a generic deduplication key which only contains the event ID.

The custom deduplication is gated behind an Unleash toggle (notifications.event-deduplication.enabled) which is disabled by default.

Acceptance criteria:

• Both scenarios mentioned above are tested.
• Duplicate events are produced for each scenario.
• The tests confirm only one event is processed for each scenario.
• The tests confirm duplicates are ignored by checking the input_duplicate_event counter in Prometheus which is increased by 1 for each ignored duplicate. The metric will have tags with the bundle and application. The tags should be used in the tests.