Set default-ansible-version to 2.7 for all tenant (minus zuul)
Set default-ansible-version to 2.7 for all tenant (minus zuul)

This is to prevent to upgrade of ansible version used by jobs, if / when
zuul project switches from ansible 2.7 to 2.8 for defaults.

Change-Id: I587a70f620bcfb1069508f69df07317d7194025c
Signed-off-by: Paul Belanger <e7139c8e6c4ea75cc1c287ce081b2dc0f3ab39ec@redhat.com>

openstack-infra/project-config,openstack-infra/project-config