[ECS] [issue]: SERVICE_DESIRED_COUNT_UPDATED event is missing in Event Bridge (CloudWatch Events)

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**Which service(s) is this request for?**
ECS

**Tell us about the problem you're trying to solve. What are you trying to do, and why is it hard?**
I'm trying to get notification about ECS Service Scaling events to be sure that scaling is actually working.
But `SERVICE_DESIRED_COUNT_UPDATED` event is missing inside Event Bridge.
I have to run AWS CLI command and get info about ECS Service Desired Count and than parse than information and use as custom CloudWatch metric.

**Additional context**
How to reproduce this issue:
- Create ECS Cluster and ECS Service with Autoscaling policy (Target tracking)
- Create Event Bridge Rule and SNS Topic with email subscription
- Perform load testing against ECS Service to trigger CloudWatch Alarm (created by AutoScaling policy)
- Stop load testing and wait until ECS Service will scale-in
- Check email and see that `SERVICE_DESIRED_COUNT_UPDATED` events are missing

There is closed issue #19 related to this.

No repository files or tests are identified. Start by reviewing the ECS/EventBridge reproduction steps and related closed issue #19; done means SERVICE_DESIRED_COUNT_UPDATED events are available in EventBridge during ECS service scaling, including scale-in.

Written by the indexing model from the issue text.