Add EL9 to "register host without Puppet"

[maximiliankolb]

What changes are you introducing?

Add EL 9

Why are you introducing these changes? (Explanation, links to references, issues, etc.)

EL 9 was missing

Anything else to add? (Considerations, potential downsides, alternative solutions you have explored, etc.)

local test that command is available:

$ podman run --rm -it almalinux:8.10
# /usr/libexec/platform-python --version
Python 3.6.8

$ podman run --rm -it almalinux:9.4
# /usr/libexec/platform-python --version
Python 3.9.18

Checklists

• I am okay with my commits getting squashed when you merge this PR.
• I am familiar with the contributing guidelines.

Please cherry-pick my commits into:

• Foreman 3.12/Katello 4.14 (Satellite 6.16)
• Foreman 3.11/Katello 4.13
• Foreman 3.10/Katello 4.12
• Foreman 3.9/Katello 4.11 (Satellite 6.15; orcharhino 6.8/6.9/6.10)
• Foreman 3.8/Katello 4.10
• Foreman 3.7/Katello 4.9 (Satellite 6.14)
• Foreman 3.6/Katello 4.8
• Foreman 3.5/Katello 4.7 (Satellite 6.13; orcharhino 6.6/6.7)
• We do not accept PRs for Foreman older than 3.5.

[github-actions]

The PR preview for 7b18ce0 is available at theforeman-foreman-documentation-preview-pr-3284.surge.sh

The following output files are affected by this PR:

• Managing_Hosts/index-orcharhino.html
• Managing_Hosts/index-satellite.html

show diff

show diff as HTML

[Lennonka]

But this is for the registration with Bootstrap, which has been deprecated for who knows how long. I don't think we have even tested it on RHEL 9. Are you sure about this?