Use ansible_service_mgr fact

This patch removes some extra tasks for detecting systemd and uses
the `ansible_service_mgr` fact instead.

Partial-Bug: #1640125
Change-Id: I70f1fb61fe879011a6bfd9517f98b8c07f793a81

tasks/cinder_init_common.yml

@@ -15,10 +15,12 @@
 # limitations under the License.
 
 - include: cinder_init_upstart.yml
-  when: pid1_name == "init"
+  when:
+    - ansible_service_mgr == 'upstart'
 
 - include: cinder_init_systemd.yml
-  when: pid1_name == "systemd"
+  when:
+    - ansible_service_mgr == 'systemd'
 
 - name: Load service
   service:

tasks/main.yml

@@ -25,19 +25,6 @@
   tags:
     - always
 
-- name: Check init system
-  command: cat /proc/1/comm
-  changed_when: false
-  register: _pid1_name
-  tags:
-    - always
-
-- name: Set the name of pid1
-  set_fact:
-    pid1_name: "{{ _pid1_name.stdout }}"
-  tags:
-    - always
-
 - include: cinder_pre_install.yml
   tags:
     - cinder-install