[EKS Scalability Testing] Implement workflows to execute large scale performance test

[JayPolanco]

Description of the issue

As part of an initiative to improve our performance testing on large scale eks clusters, we need to implement workflows that scale up, install addon and execute test that runs on our 5k node cluster.

Description of changes

1. eks-performance-cluster-scaling.yml - Responsible for scaling eks-performance cluster (5k node cluster).
   • Updated to also scale up leader node group dynamically. This node group has max of 1 node t3.xlarge
   • Scales up on Sunday 9am, scales down Monday 9pm
2. eks-performance-cluster-addon-install.yml - Responsible for installing the addon upon successful completion of scaling workflow

• adds the cwagent-target="true" label to all t3.medium instances in the cluster (non leader node). This ensures that cloudwatch-agent non leader pods are installed on these nodes
• gets the hostname (ip-x-x-x-x..compute.internal) and substitutes it into the tag in the override file in the test repo under test/performance/eks/resources/leader_election_overrides/base-overrides.yml
• installs the addon with helm, with the override file --values

3. eks-performance-cluster-tests.yml - responsible for executing the test in the test repo (eks_performance_test.go)
   • Updated check-trigger to ensure tests are only ran if the cluster has active nodes
   • installs sample applications use kubectl (petclinic-sample-app in test repo)
   • cleans up once test is complete

License

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Tests

Cluster Scaling Workflow - https://github.com/aws/amazon-cloudwatch-agent/actions/runs/16512847744/job/46697932764
Addon Install Workflow - https://github.com/aws/amazon-cloudwatch-agent/actions/runs/16523571905/job/46731027008
Performance Test Workflow - https://github.com/aws/amazon-cloudwatch-agent/actions/runs/16526410774/job/46740785992

Requirements

Before commiting your code, please do the following steps.

1. Run make fmt and make fmt-sh
2. Run make lint

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