Changes

gitlab: use custom docker:dind image
The current docker:dind container has broken default seccomp filter that 
results in clone3 being blocked, which in turn breaks Fedora 35 rawhide.
This custom image has a workaround that causes the seccomp filter to 
return ENOSYS for clone3 instad of EPERM, thus triggering glibc to 
fallback to clone correctly.
Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>

ci: refresh centos-stream container
It is no longer possible to just install an extra package to run regular 
centos into centos stream.
Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>