Clean the default security group
Clean the default security group

It's not removed when deleting the users and the projects.

Change-Id: Ib5de0885dcbfb558a48cdd20ae3ccc47b7f23748
Signed-off-by: Cédric Ollivier <d48310251a4a484d041bc5d09a9ac4d86d20f793@orange.com>

opnfv/functest,opnfv/functest