Move swiftclient default test node to trusty.
Move swiftclient default test node to trusty.

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

Change-Id: I4409651804909e52d8a70cc0a71af0256063cd52

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