Enable the queue for the Prometheus Remote Write Exporter internally (#…

…2974)

* Enable queue for the Prometheus Remote Write Exporter internally

This is a follow up to #2951.

When we disable the queue completely, it causes the export to happen
not in a consumer goroutine. Enable the queue internally that export
gets its own goroutine not to block the entire collector pipeline.

* Set a default queue size

exporter/prometheusremotewriteexporter/factory.go

@@ -66,6 +66,13 @@ func createMetricsExporter(_ context.Context, params component.ExporterCreatePar
 		params.Logger,
 		prwe.PushMetrics,
 		exporterhelper.WithTimeout(prwCfg.TimeoutSettings),
+		exporterhelper.WithQueue(exporterhelper.QueueSettings{
+			Enabled:      true,
+			NumConsumers: 1,
+			QueueSize:    10000,
+			// TODO(jbd): Adjust the default queue size
+			// and allow users to modify the queue size.
+		}),
 		exporterhelper.WithRetry(prwCfg.RetrySettings),
 		exporterhelper.WithShutdown(prwe.Shutdown),
 	)