The incus-agent subpackage currently requires the incus main package. This makes it impossible to install the agent in a virtual machine by installing just this package as it will also install all of incus.

It should be turned to a recommends or ideally we should have a incus-agent-host-support package where we add all the dependencies for the agent to be provided from the host perspective and keep the incus-agent free of other dependencies.

Reproducible: Always

Steps to Reproduce:
1. Install incus-agent package
Actual Results:
incus package is installed as well

Expected Results:
no other package installed