Disable Designate DevStack gate on stable/havana+icehouse
Disable Designate DevStack gate on stable/havana+icehouse

Designate's DevStack gate is only supported on master + future stable
branches.

Change-Id: I1fafefc787561c3bcd340e61fdd912abf19d0308

noorul/os-project-config,citrix-openstack/project-config,Tesora/tesora-project-config,anbangr/osci-project-config,dongwenjuan/project-config,noorul/os-project-config,coolsvap/project-config,osrg/project-config,Tesora/tesora-project-config,osrg/project-config,openstack-infra/project-config,citrix-openstack/project-config,anbangr/osci-project-config,open-switch/infra_project-config,open-switch/infra_project-config,coolsvap/project-config,dongwenjuan/project-config,openstack-infra/project-config