Update releases, bootstrap Docker following upstream's method, and apply minor fixes

[egypcio]

by merging these changes, we:

• update the versions of installed components;
• define an easier way to config the version for components to be installed;
• install Docker following the official method described by the upstream project;
• mention the usage of newgrp if one is installing it all manually;
• set octavia_ovn=true while installing CSO via helm;
• create the .gitignore to avoid tracking the cluster-settings.env file;
• keep the OS support as is, supporting Debian only but not limited to Debian 12.

here we would then have the following release versions:

CAPI_RELEASE=1.9.4          # clusterctl
HELM_RELEASE=3.17.1         # helm
KIND_RELEASE=0.26.0         # kind
KUBERNETES_RELEASE=1.31.6   # kubectl