Use config_template as a collection

Since we still use ceph-ansible that has their own implementation of
config_template module it's worth to use mentioned module as a collection
explicitly.

Depends-On: https://review.opendev.org/c/openstack/openstack-ansible/+/819814



Change-Id: Ia6d0d1a3c70d5bada324e7ccdda8427c7735884a

tasks/rally_post_install.yml

@@ -14,7 +14,7 @@
 # limitations under the License.
 
 - name: Drop Rally config
-  config_template:
+  openstack.config_template.config_template:
     src: "rally.conf.j2"
     dest: "{{ rally_etc_directory }}/rally.conf"
     owner: "{{ rally_system_user_name }}"