[e2e test] Need to test mutation of replica of Pod(s)

Today, all the tests are covering static replica of Pods, e.g. 1 replica. We need to enhance these tests to cover following

* increase the replica for a deployment of K8S service from 1 to 3 and verify all 3 targets are becoming healthy , and traffic are passing
* decrease the replica for a deployment of K8S service from 3 to 2, and verify 1 target are being drained
* increase the replica for a deployment of K8S service export from 1 to 3 and verify all 3 targets are becoming healthy , and traffic are passing
* decrease the replica for a deployment of K8S service export from 3 to 2, and verify 1 target are being drained

Locate the existing end-to-end tests that cover static Pod replica counts and start by understanding how Kubernetes service and service export deployments, targets, health, traffic, and draining are verified. Extend coverage for scaling 1→3 and 3→2 in both cases; done means all new targets become healthy and pass traffic, while removed targets are drained.

Written by the indexing model from the issue text.