CI: Drop centos8s and rocky8 jobs

After I3f7b480519aea38c3927bee7fb2c23eea178554d kolla-ansible
does not support EL8.

Those will be readded as Rocky9 via [1].

[1]: https://review.opendev.org/c/openstack/kayobe/+/855656

Change-Id: I6c3f9d8c54d0c6819092bd68b724a28048ac9e16

zuul.d/project.yaml

@@ -11,55 +11,25 @@
         - kayobe-tox-ansible-syntax
         - kayobe-tox-ansible
         - kayobe-tox-molecule
-        - kayobe-overcloud-centos8s
-        - kayobe-overcloud-rocky8
         - kayobe-overcloud-ubuntu-jammy
-        - kayobe-overcloud-tls-centos8s
-        - kayobe-overcloud-host-configure-centos8s
-        - kayobe-overcloud-host-configure-rocky8
         - kayobe-overcloud-host-configure-ubuntu-jammy
-        - kayobe-overcloud-upgrade-centos8s
         - kayobe-overcloud-upgrade-ubuntu-focal
-        - kayobe-seed-centos8s
-        - kayobe-seed-rocky8
         - kayobe-seed-ubuntu-jammy
-        - kayobe-seed-images-centos8s
-        - kayobe-seed-upgrade-centos8s
         - kayobe-seed-upgrade-ubuntu-focal
-        - kayobe-seed-vm-centos8s
-        - kayobe-seed-vm-rocky8
         - kayobe-seed-vm-ubuntu-jammy
-        - kayobe-infra-vm-centos8s
-        - kayobe-infra-vm-rocky8
         - kayobe-infra-vm-ubuntu-jammy
-
     gate:
       jobs:
         - kayobe-tox-ansible-syntax
         - kayobe-tox-ansible
         - kayobe-tox-molecule
-        - kayobe-overcloud-centos8s
-        - kayobe-overcloud-rocky8
         - kayobe-overcloud-ubuntu-jammy
-        - kayobe-overcloud-tls-centos8s
-        - kayobe-overcloud-host-configure-centos8s
-        - kayobe-overcloud-host-configure-rocky8
         - kayobe-overcloud-host-configure-ubuntu-jammy
-        - kayobe-overcloud-upgrade-centos8s
         - kayobe-overcloud-upgrade-ubuntu-focal
-        - kayobe-seed-centos8s
-        - kayobe-seed-rocky8
         - kayobe-seed-ubuntu-jammy
-        - kayobe-seed-upgrade-centos8s
         - kayobe-seed-upgrade-ubuntu-focal
-        - kayobe-seed-vm-centos8s
-        - kayobe-seed-vm-rocky8
         - kayobe-seed-vm-ubuntu-jammy
-        - kayobe-infra-vm-centos8s
-        - kayobe-infra-vm-rocky8
         - kayobe-infra-vm-ubuntu-jammy
-
     experimental:
       jobs:
-        - kayobe-seed-images-rocky8
         - kayobe-seed-images-ubuntu-jammy