Adapt puppet master decommission script for puppet 7

Successfully ran the following on puppet master (those worker[6-2] are stopped). I've tested with worker[6-4] (2 left to decommission worker[3-2])

root@pergamon:~# puppetserver ca clean --certname rancher-node-staging-rke2-worker6.internal.staging.swh.network
Certificate for rancher-node-staging-rke2-worker6.internal.staging.swh.network has been revoked
Cleaned files related to rancher-node-staging-rke2-worker6.internal.staging.swh.network
root@pergamon:~# puppetserver ca list --certname rancher-node-staging-rke2-worker6.internal.staging.swh.network
Missing Certificates:
    rancher-node-staging-rke2-worker6.internal.staging.swh.network

root@pergamon:~# /usr/local/sbin/swh-puppet-master-decommission rancher-node-staging-rke2-worker4.internal.staging.swh.network rancher-node-staging-rke2-worker3.internal.staging.swh.network
++ echo rancher-node-staging-rke2-worker4.internal.staging.swh.network rancher-node-staging-rke2-worker3.internal.staging.swh.network
++ tr -s '[:blank:]' ,
+ server_list=rancher-node-staging-rke2-worker4.internal.staging.swh.network,rancher-node-staging-rke2-worker3.internal.staging.swh.network
+ puppetserver ca clean --certname rancher-node-staging-rke2-worker4.internal.staging.swh.network,rancher-node-staging-rke2-worker3.internal.staging.swh.network
Certificate for rancher-node-staging-rke2-worker4.internal.staging.swh.network has been revoked
Cleaned files related to rancher-node-staging-rke2-worker4.internal.staging.swh.network
Certificate for rancher-node-staging-rke2-worker3.internal.staging.swh.network has been revoked
Cleaned files related to rancher-node-staging-rke2-worker3.internal.staging.swh.network

Refs. swh/infra/sysadm-environment#5539 (closed)

Refs. swh/infra/sysadm-environment#5547 (closed)