[azure_functions] Rename properties field to properties.raw when it contains invalid JSON

[devamanv]

Proposed commit message

If the azure.properties field in a log event is a string (instead of a structured object), the pipeline renames it to azure.properties.raw. This prevents Elasticsearch from rejecting the document due to a type conflict, allowing the event to be successfully indexed while preserving the original data for further processing or inspection.

Something similar was done for Azure Platform Logs, PR here

Note: We do not want to decide how to manage the invalid JSON that comes from Azure services.
With this approach, users have an option to decide how they want to process data in the .raw field using a custom pipeline.

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 https://github.com/elastic/obs-integration-team/issues/417
• Relates https://github.com/elastic/obs-integration-team/issues/415
• Relates New Azure Functions logs format? #11729

Screenshots

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[elastic-sonarqube]

Quality Gate failed

Failed conditions
77.3% Coverage on New Code (required ≥ 80%)

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[elasticmachine]

💚 Build Succeeded

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• Commit: b855576

cc @devamanv

[devamanv]

Closing this PR as we have decided to replace single quotes with double whenever there's an invalid JSON embedded in the properties field.