Support for lightweight or combined System VMs for small-scale and edge deployments

### The required feature described as a wish

### Problem's description
Currently, Apache CloudStack deploys multiple System VMs (Virtual Router, Secondary Storage VM, and Console Proxy VM) with a standard baseline of resource allocation. While this architecture is excellent for scalability and fault isolation in medium to large data centers, it introduces a disproportionate resource overhead (RAM and CPU) in very small environments, home labs, or Edge computing deployments.

In environments with limited physical resources, the mandatory deployment of separate, full-sized System VMs consumes a significant percentage of the available host capacity before any user workload is even launched.

### Proposed Solution
We propose introducing a less monolithic approach for System VMs in small-scale deployments. Potential solutions could include:

1. **Lightweight System VMs:** Provide an official "micro" template for System VMs (e.g., based on Alpine Linux or a heavily stripped-down OS) that consumes significantly less baseline RAM/CPU.
2. **Combined System VM:** Introduce a configuration flag to allow combining the roles of the SSVM and CPVM (and potentially basic VR features) into a single, unified System VM for environments that do not require high availability or massive concurrent access.
3. **Modular toggle:** Allow administrators to completely disable certain System VM agents (like Console Proxy) if they are not strictly required for their specific use case.

### Use Cases
* **Edge Computing:** Deploying CloudStack in micro-datacenters at the edge where hardware resources are heavily constrained.
* **PoC and Testing:** Lowering the barrier of entry for users and developers who want to evaluate CloudStack on smaller hardware (e.g., single-node deployments).
* **Small Private Clouds:** Small businesses that need IaaS capabilities but have very limited host nodes.

### Additional context
This suggestion arises from an architectural analysis conducted as part of a university project on Software Systems Architecture, where we identified this monolithic aspect of the System VMs as a performance bottleneck for small-scale adoption.

La issue non nomina file di implementazione, test o entry point. Inizia mappando come CloudStack distribuisce il Virtual Router, la Secondary Storage VM e la Console Proxy VM, quindi determina quale approccio proposto abbia un ambito definito e come verrebbe verificato il completamento per deployment piccoli o edge.

Scritto dal modello di indicizzazione a partire dal testo della issue.