Remove apparently unneeded parameters

It seems cellMessageBusInstance as well as rabbitMqClusterName aren't
valid, at least in those locations.
This leads to some failures within ArgoCD, where the
openstack-controlplane application doesn't converge properly, showing
the following persistent diff:
```
$ argocd --grpc-web app diff openshift-gitops/cifmw-demo-controlplane

===== core.openstack.org/OpenStackControlPlane openstack/openstack-control-plane ======
1187a1188
>           cellMessageBusInstance: rabbitmq
1218a1220
>           cellMessageBusInstance: rabbitmq-cell1
1533a1536
>           rabbitMqClusterName: rabbitmq
```

This is mostly reflecting a change that happened in the
openstack-k8s-operators/architecture repository:
openstack-k8s-operators/architecture#694

Author: cjeanner

components/rhoso/controlplane/controlplane/openstack-controlplane.yaml

@@ -70,12 +70,10 @@ spec:
         cell0:
           cellDatabaseAccount: nova-cell0
           cellDatabaseInstance: openstack
-          cellMessageBusInstance: rabbitmq
           hasAPIAccess: true
         cell1:
           cellDatabaseAccount: nova-cell1
           cellDatabaseInstance: openstack-cell1
-          cellMessageBusInstance: rabbitmq-cell1
           noVNCProxyServiceTemplate:
             enabled: true
             networkAttachments:
@@ -302,7 +300,6 @@ spec:
           databaseInstance: openstack
           passwordSelector:
             aodhService: AodhPassword
-          rabbitMqClusterName: rabbitmq
           serviceUser: aodh
           secret: osp-secret
         heatInstance: heat