Disable ironic job for stable/icehouse
Disable ironic job for stable/icehouse

The non-voting stable/icehouse Ironic jobs are no longer passing
and have not been for some time.  Get them out of the gate until
they are fixed.

Change-Id: Icd194ec847ab98c739032a3979a8c59f6e887647
Related-bug: #1372632

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