Use ansible_user instead of ANSIBLE_REMOTE_USER env var

In 'genereate create_ceph_ansible_remote_tmp playbook' we should
be using ansible_user because the env var ANSIBLE_REMOTE_USER
might not always being set.

Change-Id: I1229d3a0cd2f08dabdcd3b47d9823f6a939cfbdb
Closes-Bug: 1886497

tripleo_ansible/roles/tripleo_ceph_run_ansible/tasks/create_ceph_ansible_remote_tmp.yml

@@ -34,8 +34,8 @@
             become: true
             file:
               path: "{{ ceph_ansible_remote_tmp }}"
-              owner: "{{ lookup('env','ANSIBLE_REMOTE_USER') | default('tripleo-admin', true) }}"
-              group: "{{ lookup('env','ANSIBLE_REMOTE_USER') | default('tripleo-admin', true) }}"
+              owner: "{{ ansible_user | default('tripleo-admin', true) }}"
+              group: "{{ ansible_user | default('tripleo-admin', true) }}"
               mode: "700"
               state: directory