Automatic merge from submit-queue (batch tested with PRs 46726, 41912, 46695, 46034, 46551)

Event aggregation: include latest event message in aggregate event

**What this PR does / why we need it**:

This changes the event aggregation behavior so that, when multiple events are deduplicated, the aggregated event includes the message of the latest related event.

This fixes an issue where the original event expires due to TTL, and the aggregate event doesn't contain any useful message.

**Which issue this PR fixes**:

fixes #45971

```release-note
Duplicate recurring Events now include the latest event's Message string
```