disk cleanup of qcow2.xz files on macOS

[benoitf]

Is this a BUG REPORT or FEATURE REQUEST? (leave only one on its own line)

/kind feature

Description

I'm creating/stopping/deleting/ podman machines quite often.
But then I noticed that in the folder

$HOME/.local/share/containers/podman/machine/qemu/

I've several files

654M Jun  9 09:34 fedora-coreos-36.20220511.dev.0-qemu.x86_64.qcow2.xz
677M Jun 17 11:23 fedora-coreos-36.20220605.2.0-qemu.x86_64.qcow2.xz
626M Jun 22 11:43 fedora-coreos-36.20220618.2.0-qemu.x86_64.qcow2.xz

I would expect that when podman is downloading a new .xz file, it cleans up the previous files as this folder is continuously growing

Steps to reproduce the issue:

1. create machines for one week and then you'll notice many files have been downloaded

Describe the results you received:
many .xz files taking disk storage

Describe the results you expected:
only latest .xz should be kept

Additional information you deem important (e.g. issue happens only occasionally):

Output of podman version:

podman version 4.1.1

Output of podman info --debug:

(paste your output here)

Package info (e.g. output of rpm -q podman or apt list podman):

(paste your output here)

Have you tested with the latest version of Podman and have you checked the Podman Troubleshooting Guide? (https://github.com/containers/podman/blob/main/troubleshooting.md)

Yes/No

Additional environment details (AWS, VirtualBox, physical, etc.):

[baude]

good idea @benoitf