Cleanup/update all deprecated cloudstack docs

[pierrelefevre]

Lots of pages still refer to our previous cloudstack architecture and not the new k3s+rancher+kubevirt setup.

[harsha5500]

Mostly in the Maintenance section:

1. https://docs.cloud.cbh.kth.se/maintenance/installKubernetesCluster/
2. Parts of VM Template https://docs.cloud.cbh.kth.se/administration/vmTemplate/
3. Internal Cloud Stack https://docs.cloud.cbh.kth.se/internal/cloudstack/

Move the above to archive.

[harsha5500]

I can manage to add some content here but need some support from @pierrelefevre and @saffronjam for writing a section for VM configuration as I dont know how the current version of VM deployments with K8s work.