Remove owner_is_tenant from RequestContext
Remove owner_is_tenant from RequestContext

This appears to be a leftover from glance, and we don't support
anything other than tenant-scoped requests.

Change-Id: Ibce0e38ee24f18de24733a35d25c90c03b46dc6e
blueprint: request-scoping-policy

ntt-sic/heat,maestro-hybrid-cloud/heat,pshchelo/heat,dims/heat,rdo-management/heat,steveb/heat,miguelgrinberg/heat,miguelgrinberg/heat,gonzolino/heat,takeshineshiro/heat,steveb/heat,cryptickp/heat,cwolferh/heat-scratch,dims/heat,NeCTAR-RC/heat,rh-s/heat,openstack/heat,cwolferh/heat-scratch,jasondunsmore/heat,srznew/heat,pratikmallya/heat,noironetworks/heat,rh-s/heat,openstack/heat,NeCTAR-RC/heat,ntt-sic/heat,jasondunsmore/heat,takeshineshiro/heat,cryptickp/heat,pshchelo/heat,maestro-hybrid-cloud/heat,dragorosson/heat,srznew/heat,rdo-management/heat,gonzolino/heat,redhat-openstack/heat,dragorosson/heat,pratikmallya/heat,noironetworks/heat,redhat-openstack/heat