Copy the old deprecated users file when upgrading

In 6.5 Elasticsearch finds the old file which breaks the way the ansible
playbook is detecting the installed users. This means that after an
upgrade to 6.5 the users still actually exist but the playbook fails
when trying to add them again as they already exist.

tasks/xpack/security/elasticsearch-security-file.yml

@@ -2,6 +2,13 @@
 - name: set fact manage_file_users
   set_fact: manage_file_users=es_users is defined and es_users.file is defined and es_users.file.keys() | length > 0
 
+- name: Copy the old users file from the old depreacted location
+  copy:
+    remote_src: yes
+    force: no # only copy it if the new path doesn't exist yet
+    src: "{{ conf_dir }}/x-pack/users"
+    dest: "{{ conf_dir }}{{ es_xpack_conf_subdir }}/users"
+
 - name: Create the users file if it doesn't exist
   copy:
     content: ""