No longer output tar from Build job

We do not have to output a tarball in the build stage anymore. Instead we can use a podman pull in the OpenSCAP scans and a skopeo copy in the sign image job.

Definition of Done

• Remove skopeo copy from staging to docker-archive in build job
• Update podman load commands in OpenSCAP scans to podman pull using the build's IMAGE_PODMAN_SHA variable to pull by digest.
• Update the Documentation stage's sign image job to perform the skopeo copy from staging to docker-archive and use the build's IMAGE_PODMAN_SHA variable to copy by digest.