Use domain_id when testing keystone_user password

Older python-openstackclient crashes with this error if no project or
domain are passed to the openstack token issue command:

  Set a scope, such as a project or domain, with --os-project-name or OS_PROJECT_NAME

The @property_hash[:domain] value is not properly populated at this time,
making the "openstack token issue" command being invoked without proper scope.

The @property_hash[:domain_id] value is however available. Using the domain_id
instead makes both older and recent python-openstackclient happy.

Closes-bug: #1654379
Change-Id: Ie23bdb7e9dd77e6ec4358c68d77671ef3c0678a6

lib/puppet/provider/keystone_user/openstack.rb

@@ -128,7 +128,7 @@ Puppet::Type.type(:keystone_user).provide(
         credentials.project_id = projects[0][:id]
       else
         # last chance - try a domain scoped token
-        credentials.domain_name = domain
+        credentials.domain_id = domain_id
       end
 
       credentials.identity_api_version = '2' if credentials.auth_url =~ /v2\.0\/?$/

spec/unit/provider/keystone_user/openstack_spec.rb

@@ -189,13 +189,13 @@ ac43ec53d5a74a0b9f51523ae41a29f0
 
     it 'checks the password with domain scoped token' do
       provider.expects(:id).twice.returns('project1_id')
-      provider.expects(:domain).returns('domain1')
+      provider.expects(:domain_id).returns('domain1_id')
       mock_creds = Puppet::Provider::Openstack::CredentialsV3.new
       mock_creds.auth_url    = 'http://127.0.0.1:5000'
       mock_creds.password    = 'foo'
       mock_creds.username    = 'foo'
       mock_creds.user_id     = 'project1_id'
-      mock_creds.domain_name = 'domain1'
+      mock_creds.domain_id = 'domain1_id'
       Puppet::Provider::Openstack::CredentialsV3.expects(:new).returns(mock_creds)
       described_class.expects(:openstack)
         .with('project', 'list', '--quiet', '--format', 'csv',