Automation: Scale machine pool tests

[yonasberhe23]

Summary

Fixes #rancher/qa-tasks#1756

• Adds e2e coverage for scaling RKE2 Amazon EC2 machine pools - scale up/down, tooltip checks, row counts, active state.
• Fixes create/upgrade tests - Fixed flakiness caused by Kubernetes version mismatches by reading versions directly from the UI dropdown instead of the API.

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