Do not create endpoints for EC2 API by default

EC2 API was removed from nova in Mitaka. It was moved to its own service
openstack/ec2-api. We even do not have packages for it in Mirantis.
Disable EC2 API creation by default to do not confuse users.

Related-Prod: PROD-16552

Change-Id: I5abdbf831c2ebebd10f81f090f306183576773fb
1 file changed