Use 'all' for ANSIBLE_VARS_PLUGIN_STAGE
Use 'all' for ANSIBLE_VARS_PLUGIN_STAGE

ANSIBLE_VARS_PLUGIN_STAGE=inventory doesn't work with implicit
localhost in Ansible 2.11, use 'all' instead.
See https://github.com/ansible/ansible/issues/72590

Change-Id: Idc9e36563854b7e6590f74f14774d506c5dbc4c3

openstack/python-tripleoclient