templates/rebase: revert to old untag package steps

[marmijo]

Partially revert [1] to the previous logic for building the list of old packages to untag from the coreos-pool. Instead of filtering out packages that are signed with an active key, only include packages that are signed with the N-2 key. If any packages are included in the current testing-devel image, we'll trust that the exception [2] introduced in [1] will cover the case where we need to handle a package that lived for multiple releases (like shim).

[1]: e5a1651
[2]:

fedora-coreos-tracker/.github/ISSUE_TEMPLATE/rebase.md

Line 50 in e5a1651

1. **The package is signed by multiple keys** including an older one. This is OK, but add it to the untaglist anyway so it gets retagged into `coreos-pool` with a newer key/signature. You'll need to untag the RPM from `coreos-pool`, run a `koji dist-repo --non-latest coreos-pool key1 key2 key3` (which will remove that RPM from the repo metadata), and then re-tag it into the pool. The RPM in the repo will now be signed with a newer signing key.