Upgrade to OKD 4.11

Also: Use Harbor (instead of Gitlab) container image registry

Gitlab CI container registry does not implement proper tag cleanup, see: https://gitlab.cern.ch/webservices/webframeworks-planning/-/issues/1017

Closes https://gitlab.cern.ch/webservices/webframeworks-planning/-/issues/1017

Related MRs:

• obsolete: machine-api-operator!4 (closed)
• obsolete: cluster-api-provider-openstack!7 (closed)
• cluster-ingress-operator!6 (merged)