Move cinder default test node to trusty.
Move cinder default test node to trusty.

This change will run all cinder python27 unittests, doc builds, and
flake8 jobs on trusty nodes.

Change-Id: I0ff9fa5016b6065c9e229b1b2c3c5a7010d7554b

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