Adapt read-only objstorage instance to run on saam as a rancher agent

• swh/infra/puppet/puppet-swh-site!684 (merged): Adapt saam's (puppet) role to have the rancher abilities
• Ensure (again) plan is sound [1] (prior to apply)
• Apply
• Integrate saam as rancher agent in production cluster [2]
• Add 'swh/objstorage-pathslicing=true' label to saam [3]
• swh/infra/ci-cd/swh-charts!307 (merged): Deploy read-only instance on rancher agent saam (+ affinity label 'swh/objstorage-pathslicing=true')
• Checks
• swh/infra/ci-cd/swh-charts!313 (merged): Migrate clients to use that objstorage-read-only
• Checks
• (manual) saam: Stop puppet agent
• (manual) saam: Stop gunicorn-swh-objstorage (icinga will cry a bit but heh)
• Checks
• Decommission gunicorn-swh-objstorage from saam

[1] #5214 (comment 162481)

[2]

curl -fL https://rancher.euwest.azure.internal.softwareheritage.org/system-agent-install.sh | sudo  sh -s - --server https://rancher.euwest.azure.internal.softwareheritage.org --label 'cattle.io/os=linux' --token <redacted> --worker

[3]

$ environment=production; kubectl --context archive-$environment-rke2 label --overwrite node saam swh/objstorage-pathslicing=true
node/saam not labeled
$ kubectl --context archive-production-rke2 get nodes --show-labels | grep objstorage-pathslicing
saam                                 Ready    worker                      4m33s   v1.26.7+rke2r1   beta.kubernetes.io/arch=amd64,beta.kubernetes.io/instance-type=rke2,beta.kubernetes.io/os=linux,cattle.io/os=linux,kubernetes.io/arch=amd64,kubernetes.io/hostname=saam,kubernetes.io/os=linux,node-role.kubernetes.io/worker=true,node.kubernetes.io/instance-type=rke2,plan.upgrade.cattle.io/system-agent-upgrader=28cf25be6a0e6cfbeca41bb84ea6e9569e82c812e77d4a9d6ad1600f,rke.cattle.io/machine=6fa27cbd-1f10-4464-90b5-e4bba59b0066,swh/objstorage-pathslicing=true

Refs. #5110 (closed)