Refactor FakeLdap to share delete code
Refactor FakeLdap to share delete code

FakeLdap is changed to implement delete_s using delete_ext_s.

Change-Id: Ibf63f6e13da830b57a9f7ea5b9689d52d7bdf690

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