cluster-autoscaler/cloudstack: Add project-id support for multi-project environments

[mperea]

This commit adds support for the optional project-id parameter in CloudStack cloud provider configuration. This is required for clusters running in CloudStack projects, as the listKubernetesClusters API returns empty results when querying by cluster ID without the projectid parameter in multi-project environments.

Changes:

• Add ProjectID field to service.Config struct
• Pass ProjectID from cloud-config to service configuration
• Include projectid parameter in all CKS API calls when configured:
  • listKubernetesClusters (GetClusterDetails)
  • scaleKubernetesCluster (ScaleCluster and RemoveNodesFromCluster)
• Update README.md to document the optional project-id parameter

The project-id parameter is optional and backwards compatible. If not specified, the API uses the default project associated with the credentials.

What type of PR is this?

/kind bug

What this PR does / why we need it:

This PR fixes a critical issue where the cluster-autoscaler fails to work with Kubernetes clusters running in CloudStack projects.

Problem: The autoscaler currently ignores the project-id configured in the cloud-config and doesn't include the projectid parameter in API calls to CloudStack. This causes the listKubernetesClusters API to return empty results even when the cluster exists, resulting in continuous errors:

Failed to refresh cloud provider config: Unable to fetch cluster with id: <cluster-id>

Solution: This PR adds support for the optional project-id parameter by:

1. Adding a ProjectID field to the service configuration
2. Including the projectid parameter in all CloudStack API calls when configured
3. Maintaining backward compatibility (parameter is optional)

Which issue(s) this PR fixes:

Special notes for your reviewer:

• The project-id parameter is optional and maintains full backward compatibility
• If not specified, the API uses the default project associated with the credentials
• All existing unit tests pass successfully (35 tests)
• The fix has been validated in a production CloudStack environment (Linube) with Kubernetes v1.33.1
• The implementation follows the same pattern used in other CloudStack API calls

Testing performed:

cd cluster-autoscaler
go test ./cloudprovider/cloudstack/... -v
# Result: PASS (all 35 tests passed)

Does this PR introduce a user-facing change?

cluster-autoscaler/cloudstack: Add optional project-id support for multi-project CloudStack environments. Users can now specify project-id in cloud-config to use autoscaler with clusters in CloudStack projects.

Additional documentation e.g., KEPs (Kubernetes Enhancement Proposals), usage docs, etc.:

- [CloudStack API Documentation](https://cloudstack.apache.org/api/apidocs-4.21/)
- [Updated README with project-id configuration](https://github.com/kubernetes/autoscaler/blob/fix/cloudstack-project-id-support/cluster-autoscaler/cloudprovider/cloudstack/README.md)

[linux-foundation-easycla]

The committers listed above are authorized under a signed CLA.

• ✅ login: mperea / name: Mario Perea (d843c11)

[k8s-ci-robot]

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[k8s-ci-robot]

Hi @mperea. Thanks for your PR.

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[jackfrancis]

/label area/cloudstack

[k8s-ci-robot]

@jackfrancis: The label(s) /label area/cloudstack cannot be applied. These labels are supported: api-review, tide/merge-method-merge, tide/merge-method-rebase, tide/merge-method-squash, team/katacoda, refactor, ci-short, ci-extended, ci-full. Is this label configured under labels -> additional_labels or labels -> restricted_labels in plugin.yaml?

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/label area/cloudstack

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[jackfrancis]

/ok-to-test