fix: Add new cgroup layout for podman

[mattnite]

What type of PR is this?

/kind bug

Any specific area of the project related to this PR?

/area libsinsp

Does this PR require a change in the driver versions?

No

What this PR does / why we need it:

I'm finding podman cgroup names that are suffixed with /container, and because we don't handle this layout pattern, processes in podman containers are being seen as running on the host. This is seen when investigating SCAP files. This patch adds this layout to the list. For example here's some output from systemd-cgls:

├─machine.slice
│ ├─libpod-conmon-a2bc7b153f034b17f358cde43a7f8c7475147e8a0d1b2573c26473244ec44ce4.scope
│ │ └─45338 /usr/bin/conmon --api-version 1 -c a2bc7b153f034b17f358cde43a7f8c7475147e8a0d1b2573c26473244ec44ce4 -u a2bc7b153f034b17f358cde43a7f8c7475147e8a0d1b2573c26473244ec44ce4 -r /usr/bi>
│ └─libpod-a2bc7b153f034b17f358cde43a7f8c7475147e8a0d1b2573c26473244ec44ce4.scope
│   └─container
│     ├─45341 nginx: master process nginx -g daemon off;
│     ├─45366 nginx: worker process
│     ├─45367 nginx: worker process
│     ├─45368 nginx: worker process
│     └─45369 nginx: worker process

Special notes for your reviewer:

Does this PR introduce a user-facing change?:

NONE

[FedeDP]

/approve

[poiana]

LGTM label has been added.

Git tree hash: 889ef95209ac305a5f6b766b3054fc3f76bcf307

[FedeDP]

/milestone 0.14.1

[gnosek]

/approve

[FedeDP]

@gnosek missing github approve 😆

[gnosek]

oh @poiana how I hate thee

[poiana]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: FedeDP, gnosek, mattnite

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