wheel-cache: update openstack package for 8-stream

This old openstack package brings in centos-release-ceph-nautilus
which actually has an incorrect mirrorlist entry in it's .repo file
that tries to point it at the centos-8 repos [1].  When upstream
retired CentOS 8 this stopped responding.  Update to Xena (we don't
rely on any of these bits, it's just one or two packages we need
bindep to install for the wheel builds).

[1] https://bugzilla.redhat.com/show_bug.cgi?id=2051792

Change-Id: Ice106cfee23c514a5e5716d4368af9f62360e2f7

playbooks/wheel-cache/pre.yaml

@@ -18,7 +18,7 @@
     # NOTE(pabelanger): We need to install extra libraries, such as
     #  liberasurecode-devel
     # which are only part of the RDO repositories.
-    - name: Add centos-release-openstack
+    - name: Add centos-release-openstack for CentOS 7
       yum:
         name: centos-release-openstack-train
         state: present
@@ -27,9 +27,9 @@
         - ansible_distribution == "CentOS"
         - ansible_distribution_major_version == '7'
 
-    - name: Add centos-release-openstack
+    - name: Add centos-release-openstack for CentOS 8
       yum:
-        name: centos-release-openstack-ussuri
+        name: centos-release-openstack-xena
         state: present
       become: yes
       when: