Use ansible_service_mgr fact

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

Partial-Bug: #1640125
Change-Id: Iabcd8ecbf6e10ba8e65d3ac01ae635ce9294aec2

tasks/main.yml

@@ -27,19 +27,6 @@
   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: trove_pre_install.yml
   tags:
     - trove-install

tasks/trove_init_common.yml

@@ -18,11 +18,13 @@
 
 - include: trove_init_upstart.yml
   static: no
-  when: pid1_name == "init"
+  when:
+    - ansible_service_mgr == 'upstart'
 
 - include: trove_init_systemd.yml
   static: no
-  when: pid1_name == "systemd"
+  when:
+    - ansible_service_mgr == 'systemd'
 
 - name: Load service
   service: