Introduce proper steps to external update/upgrade tasks

So far the tasks for external update/upgrade were not using the step
mechanism as other tasks, we had a single step. As external
deploy/update/upgrade tasks are being used for more things nowadays,
it's likely that we'll need to go towards a similar model like we have
for deploy/update/upgrade tasks -- proper usage of steps.

For now we have just 2:

* Step 0 for setting global facts, and performing validations.

* Step 1 for actual update/upgrade tasks. (There's an upcoming change
  to run online data migrations in step 1).

Change-Id: I1933bd0eedab71caab56c0e5d93ba7927fb7c20f
Partial-Bug: #1793332

common/deploy-steps.j2

@@ -16,10 +16,10 @@
 # primary role is: {{primary_role_name}}
 {% set deploy_steps_max = 6 -%}
 {% set update_steps_max = 6 -%}
-{% set external_update_steps_max = 1 -%}
+{% set external_update_steps_max = 2 -%}
 {% set pre_upgrade_rolling_steps_max = 1 -%}
 {% set upgrade_steps_max = 6 -%}
-{% set external_upgrade_steps_max = 1 -%}
+{% set external_upgrade_steps_max = 2 -%}
 {% set post_upgrade_steps_max = 4 -%}
 {% set fast_forward_upgrade_steps_max = 9 -%}
 {% set fast_forward_upgrade_prep_steps_max = 3 -%}

docker/services/ceph-ansible/ceph-base.yaml

@@ -592,12 +592,16 @@ outputs:
                        curl_put_http_status.stdout == "201")
               when: local_ceph_ansible_fetch_directory_backup == ""
       external_update_tasks:
-        - name: set ceph_ansible_playbooks_default
+        - when: step|int == 0
           tags: ceph
-          set_fact:
-            ceph_ansible_playbooks_default: ["/usr/share/ceph-ansible/infrastructure-playbooks/rolling_update.yml"]
+          block:
+            - name: set ceph_ansible_playbooks_default
+              set_fact:
+                ceph_ansible_playbooks_default: ["/usr/share/ceph-ansible/infrastructure-playbooks/rolling_update.yml"]
       external_upgrade_tasks:
-        - name: set ceph_ansible_playbooks_default
+        - when: step|int == 0
           tags: ceph
-          set_fact:
-            ceph_ansible_playbooks_default: ["/usr/share/ceph-ansible/infrastructure-playbooks/rolling_update.yml"]
+          block:
+            - name: set ceph_ansible_playbooks_default
+              set_fact:
+                ceph_ansible_playbooks_default: ["/usr/share/ceph-ansible/infrastructure-playbooks/rolling_update.yml"]

extraconfig/services/openshift-master.yaml

@@ -436,7 +436,9 @@ outputs:
                     exit ${PIPESTATUS[0]}
 
       external_upgrade_tasks:
-        - name: set OpenShift upgrade facts
+        - when: step|int == 0
           tags: openshift
-          set_fact:
-            openshift_upgrade: true
+          block:
+            - name: set OpenShift upgrade facts
+              set_fact:
+                openshift_upgrade: true