Remove check_role_for_trust
Remove check_role_for_trust

check_role_for_trust was deprecated in Kilo and is scheduled to
be removed in Mitaka.

implements bp removed-as-of-mitaka

Change-Id: I84930c5bd4742cb971c54b482b3d1106bd03a8d1

openstack/keystone,rajalokan/keystone,mahak/keystone,klmitch/keystone,himanshu-setia/keystone,openstack/keystone,dims/keystone,himanshu-setia/keystone,cernops/keystone,cernops/keystone,mahak/keystone,openstack/keystone,ilay09/keystone,klmitch/keystone,rajalokan/keystone,ilay09/keystone,dims/keystone,rajalokan/keystone,ilay09/keystone,mahak/keystone