remove the test: test_service_enable_disable

this removes the test: test_service_enable_disable, due to race
condition. And there is a discussion in the mail list.

http://lists.openstack.org/pipermail/openstack-dev/2013-November/018867.html

Change-Id: Ib681b393944b37c720e7a245e8b19b5254d116fd
Closes-bug: 1257506
Merge "remove the test: test_service_enable_disable"