Forward messages for OpenInfra Foundation staff ML

Once the staff mailing list has been migrated to its new Mailman
site, merge this in order to forward posts destined for its old
address to the new one.

Add a test to make sure domain aliases are bein written as expected.

Change-Id: I5fea8e9ee6460417283c0ed7339d0dd447b2ff63

inventory/service/host_vars/lists.openstack.org.yaml

@@ -34,7 +34,8 @@ exim_aliases:
   superuser-owner: spam
   user-committee-owner: spam
   spam: ':fail: delivery temporarily disabled due to ongoing spam flood'
-exim_domain_aliases: {}
+exim_domain_aliases:
+  staff@lists.openstack.org: staff@lists.openinfra.dev
 exim_routers:
   - mailman_verp_router: |
       {% raw -%}

testinfra/test_lists_o_o.py

@@ -27,3 +27,9 @@ def test_mm_list_is_present(host):
 
     cmd = host.run('HOST=lists.zuul-ci.org list_lists --bare')
     assert 'zuul-discuss' in cmd.stdout
+
+def test_domain_aliases(host):
+    domain_aliases = host.file('/etc/aliases.domain')
+    assert domain_aliases.exists
+    assert domain_aliases.contains('staff@lists.openstack.org: staff@lists.openinfra.dev')
+