CI: Replace EKS 1.25 cluster with 1.27 cluster

What does this MR do?

Switches the environment and agent of the EKS pipeline jobs to target a new 1.27 EKS cluster.

Related issues

Related to #5057 (closed)

Author checklist

See Definition of done.

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Required

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Expected (please provide an explanation if not completing)

• Test plan indicating conditions for success has been posted and passes
• Documentation created/updated