Course Discovery default database is for docker.

Sandboxes don't have a 'db' host like docker will.  They need to use 'localhost' for mysql.

util/jenkins/ansible-provision.sh

@@ -172,6 +172,7 @@ PROGRAMS_VERSION: $programs_version
 COURSE_DISCOVERY_NGINX_PORT: 80
 COURSE_DISCOVERY_SSL_NGINX_PORT: 443
 COURSE_DISCOVERY_VERSION: $course_discovery_version
+COURSE_DISCOVERY_MYSQL: 'localhost'
 
 NGINX_SET_X_FORWARDED_HEADERS: True
 EDX_ANSIBLE_DUMP_VARS: true