Provide mTLS walkthrough for east-west traffic

[saiteja313]

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Describe the bug
A clear and concise description of what the bug is.

• mTLS walkthrough's provide examples for Gateway to application mtls configuration. However, this is not end to end. Considering a application with multiple backends in same mesh, we need an mtls example to shows following,

gateway -> app1 -> app2

Note: mTLS enabled between gateway -> app1, app1 -> app2, gateway-> app1 -> app2

Platform
EKS, ECS, EC2, etc.

• EKS, ECS

To Reproduce
Steps to reproduce the behavior:

1. Go to aws-app-mesh-examples/[howto-mutual-tls-file-provided]
2. Follow instructions and deploy setup.
3. Validate that mTLS is configured from gateway -> blue (color) but no mTLS between blue -> green

Additional context
Add any other context about the problem here.

• We can add a note about this stating, to enable support for east-west traffic, you can add backend listener pointing on client app pointing to server app.