Fix kolla ansible virtualenv creation on the seed

Backport: Stein, Rocky, Queens

In https://review.opendev.org/#/c/671502/ kolla ansible virtualenv
creation was modified to only happen on hosts in the kolla-ansible
inventory. However, that change omitted the seed. It passed CI because
the seed and overcloud are both in the inventory.

This change adds the seed group to the inventory_hostname lookup.

Change-Id: Ib5fb726600debee5df1f7085ea37b583bfccefcf
Story: 2006247
Task: 37368

ansible/kolla-target-venv.yml

@@ -11,9 +11,9 @@
     #  control:
     #    groups:
     #      - controllers
-    overcloud_nodes_in_kolla_inventory: >-
+    hosts_in_kolla_inventory: >-
       {{ kolla_overcloud_inventory_top_level_group_map.values() |
-      map(attribute='groups') | flatten | unique | join(':') }}
+         map(attribute='groups') | flatten | unique | union(['seed']) | join(':') }}
   tags:
     - kolla-ansible
     - kolla-target-venv
@@ -53,4 +53,4 @@
           become: True
       when:
         - kolla_ansible_target_venv is not none
-        - inventory_hostname in query('inventory_hostnames', overcloud_nodes_in_kolla_inventory)
+        - inventory_hostname in query('inventory_hostnames', hosts_in_kolla_inventory)