[sdk-trace-base] drop exporter instantiation feature

[pichlermarc]

Description

This issue is part of #5290

@opentelemetry/sdk-trace-* packages do include some features that are barely used and not present in other SDKs. One of these is the ability to instantiate exporters by overriding BasicTracerProvider functions.

The goal of this issue is to remove the code associated with that for @opentelemetry/sdk-trace-*

This issue is considered done when:

• all code related to exporter instantiation has been removed from @opentelemetry/sdk-trace-base
• tests have been updated

Additional context

• relevant code sections:

  • opentelemetry-js/packages/opentelemetry-sdk-trace-base/src/BasicTracerProvider.ts

    Lines 260 to 270 in 4179ddb

    	protected _buildExporterFromEnv(): SpanExporter | undefined {
    	const exporterName = getEnv().OTEL_TRACES_EXPORTER;
    	if (exporterName === 'none' || exporterName === '') return;
    	const exporter = this._getSpanExporter(exporterName);
    	if (!exporter) {
    	diag.error(
    	`Exporter "${exporterName}" requested through environment variable is unavailable.`
    	);
    	}
    	return exporter;
    	}

  • opentelemetry-js/packages/opentelemetry-sdk-trace-base/src/BasicTracerProvider.ts

    Lines 65 to 68 in 4179ddb

    	protected static readonly _registeredExporters = new Map<
    	string,
    	EXPORTER_FACTORY
    	>();

[pichlermarc]

I have a PR for this at #5239