remove  test_service_enable_disable in nova V3 tests

additional patch for change Ib681b393944b37c720e7a245e8b19b5254d116fd:
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: I7d54a72b45cb31e483f6833a12453d1a5cecdf61
Closes-bug: #1257506
Merge "remove  test_service_enable_disable in nova V3 tests"