Default uds-core to JSON Logging Format

[jamestexas]

Is your feature request related to a problem? Please describe.

Currently, uds-core defaults to text-based access logs, which are harder to parse and less compatible with modern logging aggregation tools. This makes debugging and integrating with tools like Fluentd, Elastic Stack, and k9s more cumbersome. Switching to JSON as the default log format would address these challenges.

Additionally, the upcoming Ambient Mode may impact or require adjustments to this configuration, so the scope of this request is focused on sidecar deployments for now.

Describe the solution you'd like

• Given an uds-core deployment with sidecars,
• When the access logging configuration defaults to JSON format,
• Then users can benefit from structured, easy-to-parse logs, simplifying integration with logging tools and improving developer experience.

Describe alternatives you've considered

• Keeping text-based logs as the default while providing clearer documentation on enabling JSON logging through Telemetry API or MeshConfig.
• Making JSON logging an optional configuration for users to enable explicitly instead of setting it as the default.
• Investigating Ambient Mode logging configurations upfront to ensure a unified approach across both sidecar and Ambient deployments.

Additional context

• Related Istio documentation: Istio Envoy Access Logs.
• Switching to JSON logging as the default could also enhance compatibility with third-party tools and reduce issues caused by custom log formats.
• Testing is needed to validate behavior in both current sidecar deployments and the potential impact on Ambient Mode logging in the future.