Remove duplicated assertion
Remove duplicated assertion

"assert_domain_enabled" method is called within "assert_user_enabled", no need perform duplicated assertion

Change-Id: I4a7895bbda614bbf31b3d3c1805389aa4465b2fb
Signed-off-by: Dave Chen <bd9a23c9ef2ab41379ad9e2a3ed5e0d59cdc0f00@intel.com>

dstanek/keystone,UTSA-ICS/keystone-kerberos,roopali8/keystone,ajayaa/keystone,cernops/keystone,rushiagr/keystone,promptworks/keystone,vivekdhayaal/keystone,rajalokan/keystone,maestro-hybrid-cloud/keystone,rajalokan/keystone,vivekdhayaal/keystone,himanshu-setia/keystone,jamielennox/keystone,rushiagr/keystone,nuxeh/keystone,idjaw/keystone,rajalokan/keystone,maestro-hybrid-cloud/keystone,dstanek/keystone,promptworks/keystone,jonnary/keystone,mahak/keystone,mahak/keystone,blueboxgroup/keystone,ilay09/keystone,takeshineshiro/keystone,openstack/keystone,ging/keystone,dims/keystone,jamielennox/keystone,dims/keystone,openstack/keystone,UTSA-ICS/keystone-kerberos,jumpstarter-io/keystone,MaheshIBM/keystone,idjaw/keystone,vivekdhayaal/keystone,ajayaa/keystone,cernops/keystone,dstanek/keystone,takeshineshiro/keystone,mahak/keystone,nuxeh/keystone,ilay09/keystone,klmitch/keystone,jumpstarter-io/keystone,ilay09/keystone,himanshu-setia/keystone,roopali8/keystone,blueboxgroup/keystone,nuxeh/keystone,rushiagr/keystone,promptworks/keystone,MaheshIBM/keystone,openstack/keystone,jonnary/keystone,jumpstarter-io/keystone,klmitch/keystone,ging/keystone