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
diff --git a/keystone/client/single.yml b/keystone/client/single.yml
index 0c70390..ebf5b5f 100644
--- a/keystone/client/single.yml
+++ b/keystone/client/single.yml
@@ -6,7 +6,6 @@
 - system.keystone.client.service.heat-cfn
 - system.keystone.client.service.keystone
 - system.keystone.client.service.neutron
-- system.keystone.client.service.nova-ec2
 parameters:
   linux:
     system: