fix: Remove CS9 support and update Ubuntu 24.04

fix: Remove CS9 support and update Ubuntu 24.04

- Remove CentOS Stream 9 from platforms (haveged not available)
- Update to Ubuntu 22.04 and 24.04 only
- Simplify tasks (remove RedHat-specific logic)
- Update molecule configuration with inject_facts_as_vars: false
- Update prepare.yml to use ansible_facts dictionary
- Add ansible.cfg file
- Remove EOL platforms (CentOS 7/8, Ubuntu 18.04/20.04)
- Update README with CentOS 9 limitation note
- Update GitHub Actions workflow matrix

Change-Id: I92a64691c9b0439fc2a62f14825dafdf386f6d4d
Signed-off-by: Anil Belur <abelur@linuxfoundation.org>