Corrected docstring for OtelCollectorExporter

[clintonb]

What was changed

Removed the incorrect reference to the OTEL_EXPORTER_OTLP_ENDPOINT environment variable.

Why?

The documentation is wrong.

Checklist

1. Closes [Feature Request] Correct docs for OtelCollectorExporter #1854

2. How was this tested:

I manually tested with my own deployment.

3. Any docs updates needed?

This is a docs update.

[CLAassistant]

All committers have signed the CLA.

[mjameswh]

Ah, that's possible. There have been many recent changes to the OTel support in Core SDK. That may have got broken at some point.

Out of curiosity, what led you to figure out this statement is correct? What was your use case for OTEL_EXPORTER_OTLP_ENDPOINT?

[clintonb]

@mjameswh Every other TS/JS library expects OTEL_EXPORTER_OTLP_ENDPOINT to be the root of HTTP Otel endpoint (e.g., http://localhost:4318). This is the only library I've come across that expects a path: http://localhost:4318/v1/metrics.

All of my deployed workloads have OTEL_EXPORTER_OTLP_ENDPOINT defined because the rest of my code relies on it. While testing the use of HTTP metrics for Temporal, I realized that the docstring is wrong. In fact, I use OTEL_EXPORTER_OTLP_ENDPOINT to create the metrics URL:

const otelMetricsEndpoint = process.env.OTEL_EXPORTER_OTLP_ENDPOINT
  ? `${process.env.OTEL_EXPORTER_OTLP_ENDPOINT}/v1/metrics`
  : undefined;