Run online migration tasks from external_update_tasks too.

The minor update procedure has been suggesting the execution of the
online db migrations step for few releases already, by the execution
of the openstack overcloud external-update run --tags online_upgrade.
However, this command has never executed any task at all as the
online_upgrade tasks belong to the external_upgrade_tasks section.
Instead of changing the interface in all releases by modifying the docs
let's just fix this in the code.

Change-Id: I4453e7c755cccc52bb135a14be1b04fdea53de6b
Closes-Bug: #1900467
(cherry picked from commit d18209799c)

deployment/cinder/cinder-api-container-puppet.yaml

@@ -448,7 +448,7 @@ outputs:
             - { 'path': /var/log/containers/httpd/cinder-api, 'setype': svirt_sandbox_file_t, 'mode': '0750' }
       external_upgrade_tasks:
         - when: step|int == 1
-          block:
+          block: &cinder_online_db_migration
             - name: Online data migration for Cinder
               command: "{{ container_cli }} exec cinder_api cinder-manage db online_data_migrations"
               delegate_to: "{{ groups['cinder_api'][0] }}"
@@ -470,6 +470,9 @@ outputs:
                   - cinder_api
                   - cinder_api_cron
                 tripleo_delegate_to: "{{ groups['cinder_api'] | default([]) }}"
+      external_update_tasks:
+        - when: step|int == 1
+          block: *cinder_online_db_migration
       external_deploy_tasks:
         - name: Clean up legacy Cinder keystone catalog entries
           become: true

deployment/ironic/ironic-api-container-puppet.yaml

@@ -322,7 +322,7 @@ outputs:
             - { 'path': /var/log/containers/httpd/ironic-api, 'setype': svirt_sandbox_file_t, 'mode': '0750' }
       external_upgrade_tasks:
         - when: step|int == 1
-          block:
+          block: &ironic_online_db_migration
             - name: Online data migration for Ironic
               command: "{{ container_cli }} exec ironic_api ironic-dbsync --config-file /etc/ironic/ironic.conf online_data_migrations"
               delegate_to: "{{ groups['ironic_api'][0] }}"
@@ -330,3 +330,6 @@ outputs:
               tags:
                 - online_upgrade
                 - online_upgrade_ironic
+      external_update_tasks:
+        - when: step|int == 1
+          block: *ironic_online_db_migration

deployment/nova/nova-conductor-container-puppet.yaml

@@ -263,7 +263,7 @@ outputs:
                 state: yes
       external_upgrade_tasks:
         - when: step|int == 1
-          block:
+          block: &nova_online_db_migration
             - name: Online data migration for Nova
               command: "{{ container_cli }} exec nova_conductor nova-manage db online_data_migrations"
               delegate_to: "{{ groups['nova_conductor'][0] }}"
@@ -285,3 +285,6 @@ outputs:
                 tripleo_containers_to_stop:
                   - nova_conductor
                 tripleo_delegate_to: "{{ groups['nova_conductor'] | default([]) }}"
+      external_update_tasks:
+        - when: step|int == 1
+          block: *nova_online_db_migration