Deprecate [agent]manage_agent_boot

[Jay Faulkner]

The configuration option [agent]manage_agent_boot was designed for a time where it was possible for an Ironic deployer to use and run their own PXE booting infrastructure and DHCP and have Ironic utilize it.

This should not be a configuration we continue to support, as anyone with this option enabled are effectively walled off from huge portions of Ironic's featureset.

[OpenStack Infra (hudson-openstack)]

Related fix proposed to branch: master
Review: https://review.opendev.org/c/openstack/ironic/+/923328

[Iury Gregory Melo Ferreira (iurygregory)]

Setting importance and assigning to Jay.

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.opendev.org/c/openstack/ironic/+/923328
Committed: https://opendev.org/openstack/ironic/commit/465bedbe7ff4a0e33f4b8ecdc5bd8e85f7c3598c
Submitter: "Zuul (22348)"
Branch: master

commit 465bedbe7ff4a0e33f4b8ecdc5bd8e85f7c3598c
Author: Jay Faulkner <email address hidden>
Date: Tue Jul 2 15:20:52 2024 -0700

    Deprecate [agent]/manage_agent_boot

    This configuration directive is completely untested, undocumented,
    and requires deployers to manually configure significant
    infrastructure for it. It also bypasses several deploy-time sanity
    checks around whether or not we expect the server to boot.
    Deprecating it for removal in 2025.2 release.

    Related-bug: #2071741
    Change-Id: Id73d9097e9e4152c7b635a4269b548c9dbdda0a6