[ECS] [request]: Customize Service Connect configuration

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**Tell us about your request**
Allow customization of Service Connect configuration related to retries and timeout per target

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

**Tell us about the problem you're trying to solve. What are you trying to do, and why is it hard?**
Today SC will retry twice on connection failure or 503 responses. Customize this policy based on the target service would be great. For example disable retries for requests to a "Process Payment" service that is not idempotent.
When Authentication is supported, this could be extended to define which services require Auth and which don't.

**Are you currently working around this issue?**
Don't use Service Connect

The issue concerns ECS Service Connect retry and timeout behavior per target, but it names no repository files, tests, or entry points. Start by reviewing the Service Connect configuration and documented behavior, then define the supported per-target policy and its completion criteria.

Written by the indexing model from the issue text.