Deployment on Edge Controller and Edge Nodes with Ubuntu 20.04

[oEscal]

On this pull request we changed the playbooks in order to deploy OpenNESS in environments with both Edge Controller and Edge Nodes with Ubuntu 20.04 installed. It is important to notice that the deployment for nodes and controller with CentOS 7.9 still works.

We tested the deployment for the minimal flavor and with (and without) the deployment of the Istio service mesh in the following environment:

1 Controller Node (with Ubuntu 20.04):
    RAM: 16GB
    CPU: 8 VCPUs
1 Edge Node (with Ubuntu 20.04):
    RAM: 10GB
    CPU: 4 VCPUs

Note: this pull request is a follow up of the pull request #125, with some modifications for the deployment to work on Edge Controllers with Ubuntu 20.04.