Fedora-ELN composes don't contain the kernel-64k package on aarch64

It is getting built, but is not included in the compose repo because it’s marked as “build root-only”, the default for packages not explicitly added to one of the repos.

To be in a repo, it needs to be in prepopulate.json in pungi-fedora, eln branch. [1]

The kernel-64k packages are already part of the same workloads for both ELN and CentOS Stream 10. [2]

[1] https://pagure.io/pungi-fedora/commits/eln
[2] https://github.com/minimization/content-resolver-input/blob/main/configs/sst_kernel_maintainers-kernel-base-eln.yaml