Update to use consistent docker extra env vars

Update to use consistent docker extra env vars

This playbook was still referencing the old version of the
ceph_*_docker_extra_env but only for Ceph MONs and Ceph NFS. This
playbook was not kept up-to-date when updating the
ceph_*_docker_extra_env variables to add the '-e' option to docker.
That's because the addition of '-e' breaks this playbook as it requires
a comma separated list of variables for the 'env:' docker module
parameter. Therefore this change just makes the playbook consistently
broken by referencing the same variable throughout.