Unable to mark events as FAILED in MongoDB event registry via the staleness monitor

[Xadhoodin]

When StalenessMonitorConfiguration runs on application startup, it schedules a task to mark stale events as FAILED.

This leverages the method findByStatus(Status status) defined in the EventPublicationRepository interface.

However, MongoDbEventPublicationRepository doesn't implement that method and relies on the default implementation in the said interface, always returning an empty collection. With no events fetched, stale events get never set to FAILED, making reprocessing them impossible

[odrotbohm]

That's merged, polished, and back-ported. Please give the snapshots a try.