Always copy kernels to internal storage if possible

The S3 artifact storage for the Gitlab jobs is hosted on AWS. Without publish_elsewhere, Beaker will repeatedly hit the AWS buckets from outside AWS, which costs 0.09USD/GB. This nicely adds up 🙈.

For internal jobs, this is mitigated by publish_elsewhere which copies the kernel RPMs and tarballs to internal S3 storage closer to Beaker. This results in transit gateway costs of ~0.02USD/GB (iiuc the AWS cost tables correctly 🙈), which only has to be paid once.

To reduce costs for the publish_elsewhere=False, always copy to the internal S3 mirror if configured with such a bucket, and point beaker_kernel_package_url to it.

Signed-off-by: Michael Hofmann mhofmann@redhat.com