Adjust when statement for os-gnocchi-install playbook
Adjust when statement for os-gnocchi-install playbook

Minor change:
In https://review.openstack.org/#/c/411146 we adjusted the when
statement for the os-gnocchi-install playbook, which was a backport.

Making the same change to make this consistent and keep it in line.

Change-Id: Id17360a1d7526a15e345ffd3a5fcdad9bdf6d454

openstack/openstack-ansible,weezer/openstack-ansible,yanyao/openstack-ansible,BjoernT/openstack-ansible,BjoernT/os-ansible-deployment,robb-romans/openstack-ansible,yanyao/openstack-ansible,cfarquhar/openstack-ansible,openstack/openstack-ansible,BjoernT/os-ansible-deployment,robb-romans/openstack-ansible,stackforge/os-ansible-deployment,bunchc/openstack-ansible,BjoernT/openstack-ansible,cloudnull/os-ansible-deployment,weezer/openstack-ansible,cloudnull/os-ansible-deployment,stackforge/os-ansible-deployment,BjoernT/os-ansible-deployment,bunchc/openstack-ansible,os-cloud/os-ansible-deployment,os-cloud/os-ansible-deployment,cfarquhar/openstack-ansible