We removed use of these templates after platform removed yaml

While we'll eventually switch back, having unused templates around is
confusing.

Other code removed in 8f16fd28

playbooks/roles/edxapp/templates/cms.env.yaml.j2

-{{ cms_env_config | to_nice_yaml }}

playbooks/roles/edxapp/templates/lms.env.yaml.j2

-{{ lms_env_config | to_nice_yaml }}