[ECS/tasks] [request]: Service Connect Support for Scheduled ECS Tasks

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**Tell us about your request**
When we run ECS tasks directly as "service-less", there is no service connect support to communicate with ECS services.

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

**Tell us about the problem you're trying to solve. What are you trying to do, and why is it hard?**
Currently we are using App Mesh for our infrastructure which consist of ECS services and tasks. When we try to use ECS Service Connect instead of App Mesh, ECS services can communicate with each other successfully. On the other hand, there is no option for our scheduled ECS tasks to communicate with ECS services.

**Are you currently working around this issue?**
Currently we have no solution to overcome this problem.

Start by reviewing the ECS tasks and Service Connect scenario described in the issue, including the contrast with App Mesh. Done means scheduled, service-less ECS tasks can communicate with ECS services through Service Connect; the issue names no files or tests, so the implementation scope must be established first.

Written by the indexing model from the issue text.