CI: Enable CentOS 8 bifrost job

Depends-on: https://review.opendev.org/711293
Change-Id: Ida5332cf2a8ac24a25eccc487e8a11c1e975ddcc

zuul.d/project.yaml

@@ -14,8 +14,7 @@
         - kolla-ansible-debian-source
         - kolla-ansible-ubuntu-source
         - kolla-ansible-ubuntu-source-multinode-ipv6
-        # FIXME(mgoddard): Bifrost CentOS 8 support in progress.
-        # - kolla-ansible-centos8-source-bifrost
+        - kolla-ansible-centos8-source-bifrost
         - kolla-ansible-centos8-source-zun
         - kolla-ansible-ubuntu-source-zun
         - kolla-ansible-centos8-source-swift