shade is not used anymore by the `os_*` modules.
PR #40532 replaces `shade` library by `openstacksdk`. This commit clean
up some references to the old library. It's similiar to what has been
done in PR #40784.
* Establish connection through openstacksdk
* Switch from shade to openstacksdk
* fix typo in link to openstacksdk
* remove nova_client usage
* further remove of min_version from openstack modules