Apply branch excludes to either ubuntu or centos
Apply branch excludes to either ubuntu or centos

A previous change [1] added some per-branch excludes to fix
an issue with new test environment that were added in ocata.

This patch extends these excludes statements to apply to centos.

[1] - I2bfe8d1c324f3bb2ebba3db47e68c27feac281e1

Change-Id: Iadc948fa3b931081bf2333e41ea622ca483917d6

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