Remove unused variables.

These are Django defaults, but analytics-api hasn't used them
for 3 years.
https://github.com/edx/edx-analytics-data-api/commit/788a7067ed4d96507bd390523cd0269ba62fcd4c

playbooks/roles/analytics_api/defaults/main.yml

@@ -63,10 +63,6 @@ ANALYTICS_API_USERS:
 ANALYTICS_API_SECRET_KEY: 'Your secret key here'
 ANALYTICS_API_TIME_ZONE: 'UTC'
 ANALYTICS_API_LANGUAGE_CODE: 'en-us'
-ANALYTICS_API_EMAIL_HOST: 'localhost'
-ANALYTICS_API_EMAIL_HOST_USER: 'mail_user'
-ANALYTICS_API_EMAIL_HOST_PASSWORD: 'mail_password'
-ANALYTICS_API_EMAIL_PORT: 587
 ANALYTICS_API_AUTH_TOKEN: 'put-your-api-token-here'
 
 
@@ -116,11 +112,6 @@ ANALYTICS_API_SERVICE_CONFIG:
   SECRET_KEY: '{{ ANALYTICS_API_SECRET_KEY }}'
   TIME_ZONE: '{{ ANALYTICS_API_TIME_ZONE }}'
   LANGUAGE_CODE: '{{ANALYTICS_API_LANGUAGE_CODE }}'
-  # email config
-  EMAIL_HOST: '{{ ANALYTICS_API_EMAIL_HOST }}'
-  EMAIL_HOST_PASSWORD: '{{ ANALYTICS_API_EMAIL_HOST_PASSWORD }}'
-  EMAIL_HOST_USER: '{{ ANALYTICS_API_EMAIL_HOST_USER }}'
-  EMAIL_PORT: '{{ ANALYTICS_API_EMAIL_PORT }}'
   API_AUTH_TOKEN: '{{ ANALYTICS_API_AUTH_TOKEN }}'
   STATICFILES_DIRS: ['static']
   STATIC_ROOT: "{{ COMMON_DATA_DIR }}/{{ analytics_api_service_name }}/staticfiles"

playbooks/sample_vars/passwords.yml

@@ -4,7 +4,6 @@
 # The current process is described here: https://openedx.atlassian.net/wiki/x/dQArCQ
 #
 
-ANALYTICS_API_EMAIL_HOST_PASSWORD: !!null
 ANALYTICS_PIPELINE_OUTPUT_DATABASE_PASSWORD: !!null
 ANALYTICS_SCHEDULE_MASTER_SSH_CREDENTIAL_PASSPHRASE: !!null
 COMMON_HTPASSWD_PASS: !!null