Can't build SR-IOV Network Operator images

[e0ne]

CentOS 8 is EOL now [1]. It means we can't build docker images now because of this error:

CentOS Linux 8 - AppStream 110 B/s | 38 B 00:00
Error: Failed to download metadata for repo 'appstream': Cannot prepare internal mirrorlist: No URLs in mirrorlist

We need to update base images to fix our images build

[1] https://forums.centos.org/viewtopic.php?f=54&t=78708

[e0ne]

I tested with registry.access.redhat.com/ubi8/ubi:8.5-226 image:

Last metadata expiration check: 0:00:03 ago on Wed Feb  2 16:38:32 2022.
No match for argument: mstflint
Error: Unable to find a match: mstflint
The command '/bin/sh -c yum -y update && ARCH_DEP_PKGS=$(if [ "$(uname -m)" != "s390x" ]; then echo -n ${MSTFLINT} ; fi) && yum -y install hwdata $ARCH_DEP_PKGS && yum clean all' returned a non-zero code: 1

@zshi-redhat @pliurh do you have any suggestions what base image we should use? I tested with quay.io/centos/centos:stream9 and it works for me. Maybe it's better to use centos8 for now with updated repos?