Protect only the harness pid during cancellation sweeps. The host recorded parent pid can be stale on Windows and recycled onto the hung command; adding that raw pid to the protected set spared the cancellation target and pruned its whole subtree from cleanup.
Keep protected-subtree pruning rooted at the harness itself, which still spares its real workers while allowing the timed-out target to be reaped.
Fixes#7452
roboomp
dc22ea5dad