Samples using deprecated APPMESH_VIRTUAL_NODE_NAME

I'm working through the colorapp example, and I see the ECS tasks created use `APPMESH_VIRTUAL_NODE_NAME`

There's a warning in the [docs](https://docs.aws.amazon.com/app-mesh/latest/userguide/envoy-config.html) that this setting has been deprecated in envoy.

> The environment variables APPMESH_VIRTUAL_NODE_NAME and APPMESH_RESOURCE_NAME are no longer supported in Envoy version 1.15.0 or later. However, they're still supported for existing meshes. Instead of using these variables with Envoy version 1.15.0 or later, use APPMESH_RESOURCE_ARN for all App Mesh endpoints.

I'm running `v1.21.0.0-prod` and everything works fine. Should the example be updated to use `APPMESH_RESOURCE_ARN`?

Start in the colorapp example by searching for APPMESH_VIRTUAL_NODE_NAME and reviewing how the ECS task environment is assembled. Compare the current configuration with the linked App Mesh documentation and verify that the sample uses APPMESH_RESOURCE_ARN without breaking its existing deployment flow.

Written by the indexing model from the issue text.