Draft: Update Fedora ELN gating policy to use 'eln' as the product version

This is a follow-up to !4500 (merged). After adding the ELN gating policy we realized there were issues with the 'fedora-eln' product version name, so we've now adjusted Bodhi to query for 'eln' instead, and updated the Greenwave policy for that. So now we need to make the same change here so the gating policy will finally be applied.

Signed-off-by: Adam Williamson awilliam@redhat.com