feat: allow force for cluster upgrades

[amdove]

Description

• Add force_maintenance config option for both AWS EKS and Azure AKS clusters
• AWS: Sets ForceUpdateVersion to override upgrade-blocking readiness checks (EKS Insights)
• Azure: Sets ForceUpgrade to bypass PodDisruptionBudget constraints during upgrades

Test plan

• Verify config parsing with force_maintenance: true in ptd.yaml
• Test Azure AKS upgrade with force_maintenance enabled
• Test AWS EKS upgrade with force_maintenance enabled

Code Flow

Category of change

• Bug fix (non-breaking change which fixes an issue)
• Version upgrade (upgrading the version of a service or product)
• New feature (non-breaking change which adds functionality)
• Build: a code change that affects the build system or external dependencies
• Performance: a code change that improves performance
• Refactor: a code change that neither fixes a bug nor adds a feature
• Documentation: documentation changes
• Breaking change (fix or feature that would cause existing functionality to not work as expected)

Checklist

• I have reviewed my own diff and added inline comments on lines I want reviewers to focus on or that I am uncertain about

[ian-flores]

Tested the AWS EKS path end-to-end on ganso01-staging — force upgrade worked correctly to bypass session PDBs during a 1.32 → 1.33 node group upgrade.

The unified force_maintenance naming and Azure support look good.