This patch includes changes required to run devstack on RHEL 9.
- en_US.utf8 is provided by glibc-langpack-en
- iptables command is provided by iptables-nft
- Use /etc/os-release to identify the distro in RHEL 9 as it doesn't
provide lsb_release command.
- CRB repository name is different from CentOS 9
Change-Id: I8f6d9263b24f9c2cf82e09258e2d14d7766ad337