ensure Dockerfiles using UBI8 based images are ALL being updated with updateBaseImages

At least two dockerfiles in our set are not being updated correctly to the latest UBI8 base images:

• https://github.com/redhat-developer/devspaces-images/blob/devspaces-3-rhel-8/devspaces-pluginregistry/build/dockerfiles/openvsx-builder.Dockerfile#L9
• https://github.com/redhat-developer/devspaces-images/blob/devspaces-3-rhel-8/devspaces-pluginregistry/build/dockerfiles/ovsx-installer.Dockerfile#L9

There may be others. Need to scan for more places where a FROM ubi appears in any/all dockerfiles in Che and DS, and make sure they're all included in the automation for:

• https://github.com/eclipse-che/che-release/actions/workflows/update-base-images.yml