Setup managed node group for EKS

[git4rk]

Issue #, if available:

Description of changes:

• Set up managed node group for EKS
• Resolve issue in workload stack
  • Getting parameter /ibm/liberty-for-eks/ca-central-1/tCaT-liberty-eks-with-app-189627-IBMLibertyWorkloadStack-3N7OBVFDJVQM/install-outputs...

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[git4rk]

@vsnyc Please review.