[pkg/stanza] Improve error logs produced by transformer processors

[douglascamata]

Description

This improves the error messages of the log transformers processors to include the log file path and the original log record, effectively allowing users to quickly debug and investigate deeper the reason for the problem without having to use the debug exporter or using the highest verbosity level.

Here's an example of one of these failures:

2025-01-17T15:38:13.637Z error helper/transformer.go:114 Failed to process entry {"kind": "receiver", "name": "filelog", "data_type": "logs", "operator_id": "move5", "operator_type": "move", "log.file.path": "/var/log/pods/kube-system_kindnet-jxpz6_0784c9f9-ec2b-4829-aeb3-263ec66ef953/kindnet-cni/19.log", "log.record.original": "2025-01-17T15:38:07.645938111Z stderr F I0117 15:38:07.645727 1 main.go:297] Handling node with IPs: map[172.18.0.2:{}]", "error": "move: field does not exist: attributes.uid", "action": "send"}

This log line could be even more helpful if the it included the regex pattern that was matched against the entry. I'm not sure about adding it now and it could be added in the future if desired.

A small note on the name of the log keys: they could have shorter names, like body and file_path but I think we could also use the attribute names from the semantic conventions for logs. I have no preference though and I'm happy to change it if needed.

Testing

• Ran it locally in a kind cluster.
• Some unit tests were updated to ensure the log.record.original key is present in the logs.

[douglascamata]

I have no idea about why this codeowners check is failing. I didn't touch the CODEOWNERS file and rebased with main a couple times.