Rename podman buildroot package to podman-legacy

[afbjorklund]

To avoid conflict with the new buildroot 2025.05 podman package
It could have been called podman-master, which would be ironic.

But it should be updated from v3.4 to v4.9*, possibly with CNI
support enabled to avoid having to build netavark (with rust).

Closes #22105

* it would still be podman-legacy, since both 3.4 and 4.9 are EOL

https://endoflife.date/podman

But it doesn't have to run things, only work with the cri-o images?

So 5.x (quadlet) is not so important.

https://www.redhat.com/en/blog/podman-new-network-stack

• CNI Deprecation is a Bad Decision – Request to Retain Support containers/podman#25730

---

In order to switch to BR "podman", the socket permissions need fixing:

• Allow minikube ssh login as root instead of as docker #22360

This package adds a "podman" group that works like the "docker" group:

• https://docs.docker.com/engine/install/linux-postinstall/#manage-docker-as-a-non-root-user

[k8s-ci-robot]

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[afbjorklund]

ok-to-build-iso

[minikube-bot]

Hi @afbjorklund, building a new ISO failed for Commit 9d46dc9
See the logs at:
https://storage.cloud.google.com/minikube-builds/logs/22435/9d46dc9/iso_build.txt

[afbjorklund]

Same jenkins issue as in #22434 (comment)