[service] [request]: Container Insights - Change metric collection interval for Cluster and Service-Level Metrics

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**Tell us about your request**
The ability to change the metric collection interval for Cluster and Service-Level metrics on Container Insights.

The Instance-Level metrics already has this feature and it would be convenient if we could do it for the Cluster and Service-Level metrics.

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

**Tell us about the problem you're trying to solve. What are you trying to do, and why is it hard?**
Collecting metrics every minute is a little wasteful in my current setup. Having the ability to change this to every 5 minutes would be more cost efficient. While debugging issues, it would also be convenient to temporarily lower this interval to every 10 seconds, or so.
As the number of clusters and services grow, so do our CloudWatch costs, to the point I will have to disable Container Insights.

The request concerns ECS Container Insights and its Cluster- and Service-Level metric intervals; start by reviewing how the existing Instance-Level interval setting works. No implementation files, tests, or entry points are identified in the issue, so completion would require defining the supported interval behavior and validating its effect on metric collection and cost.

Written by the indexing model from the issue text.