Removed EDXAPP_JWT_AUDIENCE override from discovery Docker settings

All services should use common_vars, so there is no need for an override.

LEARNER-817

docker/build/discovery/ansible_overrides.yml

@@ -8,7 +8,6 @@ COMMON_MYSQL_MIGRATE_PASS: '{{ DISCOVERY_MYSQL_PASSWORD }}'
 EDXAPP_LMS_BASE: 'edx.devstack.lms:18000'
 EDXAPP_LMS_ROOT_URL: 'http://{{ EDXAPP_LMS_BASE }}'
 EDXAPP_LMS_PUBLIC_ROOT_URL: 'http://localhost:18000'
-EDXAPP_JWT_AUDIENCE: 'lms-key'
 
 DISCOVERY_MYSQL: 'edx.devstack.mysql'
 DISCOVERY_DJANGO_SETTINGS_MODULE: 'course_discovery.settings.devstack'