[contribfest] use env var utility functions to setup diagnostics logging

[pichlermarc]

Description

Description

Important

This issue is reserved for attendees of OpenTelemetry ContribFest at KubeCon EU 2025
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marked as "good-first-issue" starting Thursday. 🙂

With open-telemetry/opentelemetry-js#5443 we've introduced new utility functions for getting getting environment variables in an OTel Spec compliant manner, and we've migrated from using the old getEnv() utility function (#2708).

However, to provide an easier upgrade-path, for users of getEnv() we've also introduced a utility function to get a log level from a string, so the mapping we now do is now obsolete and we should align it with the core repo.

The goal of this issue is to replace the diagnostics logging setup here:

opentelemetry-js-contrib/metapackages/auto-instrumentations-node/src/register.ts

Line 24 in 03350ef

diag.setLogger(new DiagConsoleLogger(), getLogLevelFromEnv());

with a setup which is the same as in the core repo.

You can then remove this code here:

opentelemetry-js-contrib/metapackages/auto-instrumentations-node/src/utils.ts

Lines 307 to 318 in 03350ef

	export function getLogLevelFromEnv(): DiagLogLevel {
	const rawLogLevel = process.env.OTEL_LOG_LEVEL;
	// NOTE: as per specification we should actually only register if something is set, but our previous implementation
	// always registered a logger, even when nothing was set. Falling back to 'INFO' here to keep the same behavior as
	// with previous implementations.
	// Also: no point in warning - no logger is registered yet
	return (
	logLevelMap[rawLogLevel?.trim().toUpperCase() ?? 'INFO'] ??
	DiagLogLevel.INFO
	);
	}

and any other code that becomes unused from this change.

To complete this issue:

• check the implementation of the new env var utility functions as well as the utility to convert strings to DiagLogLevel.
• use these new utility functions in the auto-instrumentations-node setup code
• the new utility functions do already drop blank and nullish strings, please remove any now-unncessary code
• ensure unit-tests are still passing

[danherd]

I'll take this!