Automatic merge from submit-queue
Add support of Keystone v3 'domain-name' to 'openstack-heat' cluster setup
**What this PR does / why we need it**:
Keystone v3 authentication by user name [requires the domain (name or ID)](http://developer.openstack.org/api-ref/identity/v3/index.html?expanded=password-authentication-with-scoped-authorization-detail). If `domain-name` is not provided kubelet fails as seen below:
```
kubelet: error: failed to run Kubelet: could not init cloud provider "openstack": You must provide exactly one of DomainID or DomainName to authenticate by Username
systemd: kubelet.service: main process exited, code=exited, status=1/FAILURE
systemd: Unit kubelet.service entered failed state.
systemd: kubelet.service failed.
```
To solve this I pass a new`OS_USER_DOMAIN_NAME` environment variable through openstack-heat's heat-templates to write it as `domain-name` in `/srv/kubernetes/openstack.conf`.
**Which issue this PR fixes** *(optional, in `fixes #<issue number>(, fixes #<issue_number>, ...)` format, will close that issue when PR gets merged)*: fixes#39783
**Special notes for your reviewer**:
**Release note**:
```
domain-name support for Keystone v3 added to openstack-heat cluster setup
```
52aa408aac