Remove package if service stopped and disabled

Adds a UpgradeRemoveUnusedPackages param to use
in the ansible when conditional for the removal

Adds package removal to step2 right after a service
is stopped and disabled on step2. Package updates
happen in step3 so ideally remove before that.

The package removal task has ignore_errors true
so dependencies or other issue removing packages will
not fail the upgrade workflow.

Also adds this to the upgrade environment files
for visibility and defaulting false

Change-Id: Ie4e4a2d41f7752c5a13507a7c15c6f68e203cfca
Related-Bug: 1701501
(cherry picked from commit ce0ef2fa20)

docker/services/ceilometer-agent-central.yaml

@@ -36,6 +36,11 @@ parameters:
     default: {}
     description: Parameters specific to the role
     type: json
+  UpgradeRemoveUnusedPackages:
+    default: false
+    description: Remove package if the service is being disabled during upgrade
+    type: boolean
+
 resources:
 
   ContainersCommon:
@@ -126,3 +131,8 @@ outputs:
         - name: Stop and disable ceilometer agent central service
           tags: step2
           service: name=openstack-ceilometer-central state=stopped enabled=no
+        - name: Remove openstack-ceilometer-central package if operator requests it
+          yum: name=openstack-ceilometer-central state=removed
+          tags: step2
+          ignore_errors: True
+          when: {get_param: UpgradeRemoveUnusedPackages}