feat(logging): Add structured JSON logging support for console

[tomchop]

This PR updates the logging configuration to support structured JSON logging on the console, which is crucial for correct interpretation of logs by cloud services like Google Cloud Logging (stackdriver).

Changes:

• Enhanced JsonFormatter to include severity, timestamp (UTC ISO 8601), and logger fields.
• Conditional usage of JsonFormatter for console_handler based on system.structured_log configuration.
• Robust JSON parsing for request bodies in audit logs.

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PR created automatically by Jules for task 6267569848034666326 started by @tomchop

[google-labs-jules]

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[tomchop]

Instead of reading a value from the config file, can you base it on a K8S_RUNTIME env variable being set?

[google-labs-jules]

Instead of reading a value from the config file, can you base it on a K8S_RUNTIME env variable being set?

I've updated the code to use the K8S_RUNTIME environment variable as requested, instead of the configuration setting.