Split Vault/Consul/Nomad clusters

Split the current deployment into a single cluster to a more enterprise one with 3 different clusters.

Start by reading the repository's Terraform configuration and identify how the current single deployment provisions Vault, Consul, and Nomad. Clarify the intended enterprise layout and dependencies before changing anything. Done means the deployment is represented as three distinct clusters, with configuration and documentation updated consistently.

Written by the indexing model from the issue text.