Switch container logs input to /var/log/pod/* path

[pchila]

Proposed commit message

This PR changes the input definition for ingesting k8s container logs from /var/log/containers/* to /var/log/pods/* which contains all available logs (including rotated ones) for pods running on the k8s node.

Before this change the integration would configure the elastic-agent input using the currently running container id and locating the corresponding log file under /var/log/containers/* which would point to the current log file, ignoring previously rotated log files for the container.

Checklist

• I have reviewed tips for building integrations and this pull request is aligned with them.
• I have verified that all data streams collect metrics or logs.
• I have added an entry to my package's changelog.yml file.
• I have verified that Kibana version constraints are current according to guidelines.
• I have verified that any added dashboard complies with Kibana's Dashboard good practices

Author's Checklist

• [ ]

How to test this PR locally

Related issues

• Closes [k8s provider] Look up metadata based on file path elastic-agent#5164
• Relates Switch k8s input paths to /var/log/pods/* to ingest rotated container logs elastic-agent#6583

Screenshots

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Quality Gate passed

Issues
0 New issues
0 Fixed issues
0 Accepted issues

Measures
0 Security Hotspots
50.0% Coverage on New Code
0.0% Duplication on New Code

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cc @pchila