Only enable leapp tasks when distribution is correct

To enable idempotence in the leapp process, even if the tasks
complete a previous partial run, we add another condition over
and above the 'UpgradeLeappEnabled' heat parameter which checks
that the distribution is RedHat (CentOS does not support the
leapp tool) and distribution version is 7 (if it's 8 then the
leapp process is complete already for this host).

NOTE: This patch was originally merged like [0], due to the
dependency between pacemaker managed services and upgrade_
leapp_enabled it had to be reverted in [1]. A fix was submitted
to remove that dependency in [2], so merging it back adapted.

[0] - Ia58e2f7853056d8a4f0a54f35d91743bf0d9f2ed
[1] - I95fa9f263e89e0ed99bc42e3966acbe5973c4cc9
[2] - Iba85e99f59258ce6ef4e05ccae737b9eeb6cfc57

Co-Authored-By: Jesse Pretorius <jesse@odyssey4.me>

Change-Id: Ie3bc270fd06c32f9bad05447925640e98bdf32a4
(cherry picked from commit 13326b564f)

deployment/tripleo-packages/tripleo-packages-baremetal-puppet.yaml

@@ -119,14 +119,29 @@ outputs:
       step_config: |
         include tripleo::packages
       upgrade_tasks:
-        - name: set leapp facts
-          tags: always
+        - name: Gather missing facts
+          setup:
+            gather_subset: "distribution"
+          when: >-
+            ansible_facts['distribution'] is not defined or
+            ansible_facts['distribution_major_version'] is not defined
+          tags:
+           - always
+
+        - name: Set leapp facts
           set_fact:
-            upgrade_leapp_enabled: {get_param: UpgradeLeappEnabled}
+            upgrade_leapp_enabled: >-
+              {{ _upgradeLeappEnabled | bool and
+                 ansible_facts['distribution'] == 'RedHat' and
+                 ansible_facts['distribution_major_version'] is version('7', '==') }}
             upgrade_leapp_debug: {get_param: UpgradeLeappDebug}
             upgrade_leapp_devel_skip: {get_param: UpgradeLeappDevelSkip}
             upgrade_leapp_command_options: {get_param: UpgradeLeappCommandOptions}
             upgrade_leapp_reboot_timeout: {get_param: UpgradeLeappRebootTimeout}
+          vars:
+            _upgradeLeappEnabled: {get_param: UpgradeLeappEnabled}
+          tags:
+            - always
 
         - name: system_upgrade_prepare step 3
           tags: