Fixes #36723 - Remove Fedora/Red Hat Atomic related code

As far as I can see this has been EOL for a few years now. Red Hat
Atomic went EOL in 2021.

Fixes #36791 - Fix typo in variable name

Introduced with 510d53cd899134b54a935cdd675d69194a1f08bd

Fixes #36759 - only call allowed transpilers

CVE-2022-3874: OS command injection via ct_command and fcct_command

Instead of allowing to call any command by changing a setting, only
allow specific paths to ct/fcct. If the user needs a different path,
they can set it via settings.yaml.

Fixes #36715 - Speed up host fact retrieval

Fixes #36768: Prevent redirection to other hosts via HTTP referer header

Fixes #36763 - Use a case statement in RHSM fact parser

Fixes #36673 - Fix directory ownership for remote_execution_ssh_user

Fixes #36717 - Remove katello-agent leftovers from redhat-register.erb

fixes #36658 - only use {linux,initrd}efi for x86/64 KS PXEGrub2 EL7

Refs #36517 - Correct host search for IPv6 on subnet list

The search linked to subnet.name= instead of subnet6.name, which meant
there was nothing found.

This doesn't address the bug that it doesn't look at IPv6 subnets for
the count.