JSON logs don't work with canary releases

[alexmuller]

@Financial-Times/platforms want to set an environment of "canary" to differentiate OpenTelemetry metrics in their canary releases from the existing production metrics.

When they do this, the conditional in logger appInfo.environment !== 'production' means that logs are prettified before being drained to Splunk which means that we can't search on JSON fields.

Node.js version: 22
Impacted package(s): logger

Slack message

Steps to reproduce

1. Set environment to "canary"
2. Try to search production logs in a log aggregation tool like Splunk

Expected behaviour

Canary apps should behave like production apps.