Deployment requirements: a dedicated sunbeam client VM is not a strict requirement

Canonical mattermost [thread](https://chat.canonical.com/canonical/pl/mawoqef8utgympda6uacfckush) (Sunbeam channel).

The ssunbeam client can be installed directly on the infra node or can run on a VM on top of the infra node.

The deployment steps ([requirements](https://canonical-openstack.readthedocs-hosted.com/en/latest/how-to/install/install-canonical-openstack-using-canonical-maas/#requirements) section) incorrectly states that a VM is required.

Start with the linked requirements section in the Canonical OpenStack deployment documentation and find the statement about the Sunbeam client VM. Update it to explain that the client can be installed directly on the infrastructure node or run in a VM, and confirm that the requirements no longer describe the VM as mandatory.

Written by the indexing model from the issue text.