podman container cleanup: ignore common errors

[Luap99]

The podman container cleanup command is not really intended for human use. Instead each conmon will spawn this command after the container exit to make sure we can cleanup resources asynchronously. However this command will always race against other foreground process such as podman rm -fa. Therefore it is possible that the ctr was already removed and we should not log errors in this case.

While these errors are normally not seen as the command is int he background you can see it if you enable syslog logging and then they just spam the log with useless errors so just ignore them.

Does this PR introduce a user-facing change?

podman container cleanup command now ignore the error when the container does not exists 

[packit-as-a-service]

We were not able to find or create Copr project packit/containers-podman-23537 specified in the config with the following error:

Packit received HTTP 500 Internal Server Error from Copr Service. Check the Copr status page: https://copr.fedorainfracloud.org/status/stats/, or ask for help in Fedora Build System matrix channel https://matrix.to/#/#buildsys:fedoraproject.org.

---

Unless the HTTP status code above is >= 500, please check your configuration for:

1. typos in owner and project name (groups need to be prefixed with @)
2. whether the project name doesn't contain not allowed characters (only letters, digits, underscores, dashes and dots must be used)
3. whether the project itself exists (Packit creates projects only in its own namespace)
4. whether Packit is allowed to build in your Copr project
5. whether your Copr project/group is not private

[Luap99]

@mheon PTAL

[mheon]

LGTM

[giuseppe]

/lgtm

[openshift-ci]

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