Fix telegraf task

When enabling telegraf, task failed with "the field 'vars' has an invalid value,
which appears to include a variable that is undefined. The error was: 'dict
object' has no attribute 'telegraf_services'"

Change-Id: I6dd5c401bf9b673685ad1b4a20f85c55ce04abbc
Closes-bug: #1662807

ansible/roles/telegraf/tasks/config.yml

@@ -10,8 +10,6 @@
   with_dict: "{{ telegraf_services }}"
 
 - name: Copying over default config.json files
-  vars:
-    service: "{{ telegraf_services['telegraf_services'] }}"
   template:
     src: "telegraf.json.j2"
     dest: "{{ node_config_directory }}/telegraf/config.json"