refactor(swap_encryption/pr4): thin benchmark using BaseResource pattern

- Prepare() uses SwapNodePool + SwapDaemonSet from spec.resources
- Cleanup() is empty - PKB framework auto-deletes spec.resources
- All _pod_exec(pod, ...) calls replaced with daemonset.PodExec(...)
- DaemonSet: remove workload tools; separate PKB pods (r3457826290)
- Remove cgroup v2 unlock hack (r3457928855)
- Pre-fetch kernel source for Phase 3b
- Fix COS_CONTAINERD -> UBUNTU_CONTAINERD (r3472549985)

Author: DevVegeta