Fix: Update support CentOS9 and rm EOL CentOS 7/8

Fix: Update support CentOS9 and rm EOL CentOS 7/8

- Remove CentOS 7/8 from molecule platforms and workflows
- Add CentOS 9 (stream9) support to molecule and workflows
- Update tasks to remove CentOS 7/8 specific SSL workarounds
- Simplify version conditionals for Ubuntu 22.04+ and CentOS 9+
- Remove CentOS-8.yml vars file
- Update CentOS-9.yml and CentOS Stream-9.yml to not include virtualenv package
- Install virtualenv via pip on CentOS 9 (broken RPM deps)
- Update molecule prepare.yml to only configure EPEL for CentOS 9

Change-Id: I724192d7c84c2364b71811eff3fb535ab3cd2a0e
Signed-off-by: Anil Belur <abelur@linuxfoundation.org>