This patch fixes some bugs related legacy cnf operations below:
* Delete the "unsupported key check" of policies in TOSCA template, to
resolve `openstack vnf create` command failure due to property
validation of policies.
* Change the branch condition of legacy/sol, to resolve the
`openstack vnf scale` command failure due to keyError.
* Add interval to each retry loops of delete_wait_legacy, to resolve
the `openstack vnf delete` command failure.
And this patch revises the documentation for legacy cnf operations to