Drop centos8s jobs and broken centos8s nodesets

The OpenDev team intends on removing [1] CentOS 8 Stream nodes from
Zuul and Nodepool, so lets remove broken jobs.

1. https://lists.opendev.org/archives/list/service-announce@lists.opendev.org/thread/YHPRWKWULKJATAJZPFIZCBHS7HZJE5V2/

Change-Id: Ib82833168efc2a6e2b4f1178258840d08deb78ef
Signed-off-by: Maksim Malchuk <maksim.malchuk@gmail.com>

.zuul.d/base.yaml

@@ -2,12 +2,6 @@
 - project:
     queue: kolla
 
-- nodeset:
-    name: kolla-centos8-stream
-    nodes:
-      - name: primary
-        label: centos-8-stream
-
 - nodeset:
     name: kolla-centos-9-stream
     nodes:
@@ -32,12 +26,6 @@
       - name: primary
         label: debian-bullseye
 
-- nodeset:
-    name: kolla-centos8-stream-aarch64
-    nodes:
-      - name: primary
-        label: centos-8-stream-arm64
-
 - nodeset:
     name: kolla-centos-9-stream-aarch64
     nodes:

.zuul.d/centos.yaml

@@ -11,23 +11,6 @@
       jobs:
         - kolla-build-no-infra-wheels-centos9s-source
 
-- job:
-    name: kolla-build-centos8s-binary
-    parent: kolla-base
-    nodeset: kolla-centos8-stream
-    voting: false
-    vars:
-      base_distro: centos
-      install_type: binary
-
-- job:
-    name: kolla-build-centos8s-source
-    parent: kolla-base
-    nodeset: kolla-centos8-stream
-    vars:
-      base_distro: centos
-      install_type: source
-
 - job:
     name: kolla-build-centos9s-source
     parent: kolla-base
@@ -38,25 +21,11 @@
       base_distro_version: stream9
       install_type: source
 
-- job:
-    name: kolla-build-centos8s-source-aarch64
-    parent: kolla-build-centos8s-source
-    nodeset: kolla-centos8-stream-aarch64
-    voting: false
-
 - job:
     name: kolla-build-centos9s-source-aarch64
     parent: kolla-build-centos9s-source
     nodeset: kolla-centos-9-stream-aarch64
 
-- job:
-    name: kolla-build-no-infra-wheels-centos8s-source
-    parent: kolla-build-no-infra-wheels-base
-    nodeset: kolla-centos8-stream
-    vars:
-      base_distro: centos
-      install_type: source
-
 - job:
     name: kolla-build-no-infra-wheels-centos9s-source
     parent: kolla-build-no-infra-wheels-base