[receiver/otlpreceiver] log listener address instead of configured endpoint

[axw]

When otlpreceiver starts, it reports the configured endpoint. For example, if the collector is configured with:

receivers:
  otlp:
    protocols:
      grpc:
        endpoint: localhost:0
      http:
        endpoint: localhost:0

... then the collector will log:

2025-08-18T08:16:10.912+0800 info otlpreceiver@v0.132.0/otlp.go:117 Starting GRPC server {"resource": {"service.instance.id": "5e217dbf-3a3e-4755-b35e-2121e23bd351", "service.name": "otelcorecol", "service.version": "0.132.0-dev"}, "otelcol.component.id": "otlp", "otelcol.component.kind": "receiver", "endpoint": ":0"}
2025-08-18T08:16:10.912+0800 info otlpreceiver@v0.132.0/otlp.go:175 Starting HTTP server {"resource": {"service.instance.id": "5e217dbf-3a3e-4755-b35e-2121e23bd351", "service.name": "otelcorecol", "service.version": "0.132.0-dev"}, "otelcol.component.id": "otlp", "otelcol.component.kind": "receiver", "endpoint": ":0"}

It would be helpful (e.g. in testing) if the collector were to report to report the listener address. This way, ephemeral ports can be discovered.