Remove Tender references

The relevant code was removed from edx-platform six months ago [1][2].

[1] https://github.com/edx/edx-platform/pull/9738
[2] fec5129a493e53b10a1b63c2766dc347d9f17790

playbooks/roles/edxapp/defaults/main.yml

@@ -142,9 +142,6 @@ EDXAPP_GIT_REPO_EXPORT_DIR: '/edx/var/edxapp/export_course_repos'
 
 EDXAPP_ONLOAD_BEACON_SAMPLE_RATE: 0.0
 
-EDXAPP_TENDER_DOMAIN: "None"
-EDXAPP_TENDER_SUBDOMAIN: "None"
-
 EDXAPP_FINANCIAL_REPORTS:
   BUCKET: !!null
   ROOT_PATH: "sandbox"
@@ -743,8 +740,6 @@ generic_env_config:  &edxapp_generic_env
   EMAIL_PORT: "{{ EDXAPP_EMAIL_PORT }}"
   EMAIL_USE_TLS: "{{ EDXAPP_EMAIL_USE_TLS }}"
   FEATURES: "{{ EDXAPP_FEATURES }}"
-  TENDER_DOMAIN: "{{ EDXAPP_TENDER_DOMAIN }}"
-  TENDER_SUBDOMAIN: "{{ EDXAPP_TENDER_SUBDOMAIN }}"
   WIKI_ENABLED: true
   SYSLOG_SERVER:  "{{ EDXAPP_SYSLOG_SERVER }}"
   LOG_DIR:  "{{ COMMON_DATA_DIR }}/logs/edx"