Fix downgrade test for migration 61 on non-sqlite
Fix downgrade test for migration 61 on non-sqlite

One of the downgrade tests was failing on non-sqlite because of foreign
key constraint violation.

Change-Id: I6f85e1040ffd6e6d3222cf2c2a9bce4875f6a95f
Closes-Bug: 1409716
Partial-Bug: 1408658

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