feat(infra): Add vCluster support to Infra Provisioner

### Problem / Motivation
Currently, DevOps Bench relies on standard Kubernetes cluster provisioning which can be slow and resource-heavy for running lightweight, isolated task evaluations. Integrating virtual clusters (vCluster) will enable fast, cost-effective, multi-tenant cluster provisioning per evaluation task without requiring full physical cluster spin-up.

### Proposed Solution & Technical Details
- Extend the Infra Provisioner component to support `vcluster` as a target environment type.
- Implement automated lifecycle management for vClusters (create, configure kubeconfig context, tear down).
- Ensure network and namespace isolation between concurrent task runs within the host cluster.
- Provide configuration flags in task definitions to specify vCluster requirements.

### Acceptance Criteria
- [ ] Infra Provisioner can successfully provision and bootstrap a vCluster instance.
- [ ] Task runner can execute benchmark tasks against the provisioned vCluster context.
- [ ] Cleanup routines reliably terminate vCluster instances upon task completion.
- [ ] Integration tests and provisioner documentation added.

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/kind feature
/area infra
/priority important-soon