refactor: support ansible 2.19

Do not use ansible_managed directly

Signed-off-by: Rich Megginson <rmeggins@redhat.com>

Author: richm

tests/tasks/check_header.yml

@@ -9,8 +9,8 @@
 - name: Check for presence of ansible managed header, fingerprint
   assert:
     that:
-      - ansible_managed in content
+      - __ansible_managed in content
       - __fingerprint in content
   vars:
     content: "{{ (__file_content | d(__content)).content | b64decode }}"
-    ansible_managed: "{{ lookup('template', 'get_ansible_managed.j2') }}"
+    __ansible_managed: "{{ lookup('template', 'get_ansible_managed.j2') }}"