This patch includes changes required to run devstack on CentOS Stream 9
which has been already published in official repos by CentOS team [1]:

- Add RDO deps repository for CS9.
- remove xinetd package from installation for swift. Note that
  rsync-daemon is installed which should work fine.
- Replace genisoimage by xorriso in CS9.
- Use /etc/os-release to identify the distro in CS9 as it doesn't
  provide lsb_release command.
- Use pip from rpm package instead of from get-pip.py as done in Fedora.
- Add non-voting job devstack-platform-centos-9-stream to the check
  pipeline.

Depends-On: https://review.opendev.org/c/openstack/devstack/+/848365
Change-Id: Ic67cddabd5069211dc0611994b8b8360bcd61bef
(cherry picked from commit 5ea4c3c1)