update k8s.io/legacy-cloud-provider/OWNERS with no_parent_owners: true
update k8s.io/legacy-cloud-provider/OWNERS with no_parent_owners: true

We are no longer accepting features into k8s.io/legacy-cloud-providers.
Any kind/feature PRs must be approved by SIG Cloud Provider going forward.

Signed-off-by: Andrew Sy Kim <kim.andrewsy@gmail.com>

Kubernetes-commit: 5db1b65a262096478424402887fde949bb0aa4e0

kubernetes/legacy-cloud-providers