The slice-6 restore-test teardown failed live: DELETE /lxc/{vmid} with a form body
returns HTTP 501 'Unexpected content for method DELETE', and a booted scratch needs
force=1. Move purge/destroy-unreferenced-disks/force to the query string, send no body.
Regression test locks the contract.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
