chore: Adjust exit condition for ExporterProcAsync

This will avoid exiting on an exceptional flow on Task.WhenAny

Author: jeromelaban

src/OpenTelemetry/Internal/BatchExportTaskWorker.cs

@@ -237,7 +237,7 @@ await Task.WhenAny(
                     previousTcs.TrySetResult(true);
                 }
 
-                if (this.ShouldShutdown())
+                if (this.ShouldShutdown() || cancellationToken.IsCancellationRequested)
                 {
                     break;
                 }