container: T6702: re-add missing UNIX API socket (backport #4034)

[mergify]

Change Summary

During podman upgrade and a build from the original source the UNIX socket definition for systemd got lost in translation.

This commit re-adds the UNIX socket which is started on boot to interact with Podman.

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Code style update (formatting, renaming)
• Refactoring (no functional changes)
• Migration from an old Vyatta component to vyos-1x, please link to related PR inside obsoleted component
• Other (please describe):

Related Task(s)

• https://vyos.dev/T6702

How to test

Example:

curl --unix-socket /run/podman/podman.sock -H 'content-type: application/json' -sf http://localhost/containers/json

yields:

[{'AdjustCPUShares': False,
  'Command': 'sh',
  'Config': None,
  'Created': 1725638554,
  'Id': '816d8d00fdb069219513352bd741b05d547242166951d7044a73c51091fed6ae',
  'Image': 'docker.io/library/busybox:stable',
  'ImageID': 'sha256:87ff76f62d367950186bde563642e39208c0e2b4afc833b4b3b01b8fef60ae9e',
  'Labels': {'PODMAN_SYSTEMD_UNIT': 'vyos-container-c1.service'},
  'Mounts': [],
  'Name': '',
  'Names': ['/c1'],
  'NetworkSettings': {'Networks': {'host': {'Aliases': None,
                                            'DriverOpts': None,
                                            'EndpointID': '',
                                            'Gateway': '',
                                            'GlobalIPv6Address': '',
                                            'GlobalIPv6PrefixLen': 0,
                                            'IPAMConfig': None,
                                            'IPAddress': '',
                                            'IPPrefixLen': 0,
                                            'IPv6Gateway': '',
                                            'Links': None,
                                            'MacAddress': '',
                                            'NetworkID': 'host'}}},
  'NetworkingConfig': None,
  'Platform': None,
  'Ports': [],
  'State': 'running',
  'Status': 'Up Less than a second'}]

Smoketest result

[email protected]:~$ /usr/libexec/vyos/tests/smoke/cli/test_container.py
test_api_socket (__main__.TestContainer.test_api_socket) ... ok
test_basic (__main__.TestContainer.test_basic) ... ok
test_cpu_limit (__main__.TestContainer.test_cpu_limit) ... ok
test_dual_stack_network (__main__.TestContainer.test_dual_stack_network) ... ok
test_ipv4_network (__main__.TestContainer.test_ipv4_network) ... ok
test_ipv6_network (__main__.TestContainer.test_ipv6_network) ... ok
test_uid_gid (__main__.TestContainer.test_uid_gid) ... ok

----------------------------------------------------------------------
Ran 7 tests in 124.777s

OK

Checklist:

• I have read the CONTRIBUTING document
• I have linked this PR to one or more Phabricator Task(s)
• I have run the components SMOKETESTS if applicable
• My commit headlines contain a valid Task id
• My change requires a change to the documentation
• I have updated the documentation accordingly

---

This is an automatic backport of pull request #4034 done by [Mergify](https://mergify.com).

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