fix(rhel): Fix network ordering in upstream cloud-init

[holmanb]

Proposed Commit Message

fix(rhel): Fix network ordering in upstream cloud-init

1. NM_CONTROLLED=true should be set to allow cloud-init to wait until network
   devices are online.
2. RHEL derivatives should be using the NetworkManager renderer, so set that
   in the default config.

Fixes GH-3781

Additional Context

Issues were discovered with testing upstream-built RPMs. This should fix any remaining rhel-derivative sysconfig users (are there any?) as well as correctly prioritize NetworkManager when available.

Fixes #3781

Merge type

• Squash merge using "Proposed Commit Message"
• Rebase and merge unique commits. Requires commit messages per-commit each referencing the pull request number (#<PR_NUM>)

[holmanb]

Requesting review from @ani-sinha. I assume that this will conflict with some RHEL patches, but I think this should align upstream and downstream by both 1) selecting NetworkManager over sysconfig in the default config and 2) fix sysconfig, if it is in fact still used by any RHEL derivatives.

[blackboxsw]

While both changes seem scoped at just Redhat deriviates. Some of these changes could be "risky" to existing downstreams in that it represents a change in behavior which render our cloud.cfg.tmpl directly during package build vs a runtime changeset in the configs we write. Please separate this PR into two different PRs for discussions of each changeset so we can evaluate those separate changes more specifically to make sure we aren't missing something. One PR for dropping the NM_CONTROLLED=False logic and one PR for the cloud.cfg.tmpl.

[ani-sinha]

Thanks for this change. We have been maintaining a similar patch downstream. With this change, we can remove the downstream patch. See this patch in c9s: https://gitlab.com/redhat/centos-stream/src/cloud-init/-/commit/5129908caa1867c7f584ec8d38607cf56b20521a

[ani-sinha]

Yes we intend to make network-manager renderer default in c10s. So this is also good.

[blackboxsw]

Thank you for confiming @ani-sinha this as desired downstream for Redhat derivatives. We've agreed we can get behind this in upstream provided that these commits also declare the "BREAKING CHANGE" footer and maybe even include a ! in the commit summary to highlight the change in behavior for any redhat derivative downstream using config/cloud.cfg.tmpl during their package build process