Match configure-mirrors for CentOS wheel URLs

The configure-mirrors role in zuul-jobs expects CentOS wheels will
be in URLs like distro-ver-arch and so doesn't include "-stream"
like our wheel publishing jobs are adding. This was a necessary
distinction in order to differentiate between CentOS Linux 8 and
CentOS Stream 8 wheels, but since configure-mirrors didn't know to
tell Stream nodes to look in the other location, this was actually
broken from the moment it was introduced and we simply never noticed
until we removed the old centos-8 volume (at which point
centos-8-stream nodes no longer found any wheels).

As we no longer have centos-8 nodes, rather than try to change how
configure-mirrors works (since it may be successfully used in other
sites already and would need advance warning or complex overrides in
base jobs), simply rearrange our mirrors to mount the volumes in the
paths it expects. Once this merges I'll adjust AFS accordingly.

This partially reverts 3d776f6734.

Change-Id: I07ee7ccdd10e68f6f38ec362ce7e5d333d5fc2f7

playbooks/publish/wheel-mirror.yaml

@@ -7,20 +7,10 @@
   serial: 1
 
   pre_tasks:
-
-    # NOTE(ianw) 2021-08-04 : ansible_distribution currently reports
-    # both stream and non-stream as "CentOS" so we need to check lsb
-    # here.
-    - name: Generate AFS slug - CentOS Stream
-      set_fact:
-        afs_slug: 'centos-{{ ansible_distribution_major_version }}-stream-{{ ansible_architecture }}'
-      when: ansible_lsb.id == 'CentOSStream'
-
     - name: Generate AFS slug - CentOS
       set_fact:
         afs_slug: "{{ ansible_distribution|lower }}-{{ ansible_distribution_major_version }}-{{ ansible_architecture }}"
-      when: ansible_distribution == "CentOS" and
-            ansible_lsb.id != 'CentOSStream'
+      when: ansible_distribution == "CentOS"
 
     - name: Generate AFS slug - Debuntu
       set_fact: