fix: treat timeouts < 0 as no timeout

Otherwise we'd end up setting a deadline in the past which would cause
the request to immediately time out before it even started, which makes
no sense.

profiler/upload.go

@@ -71,7 +71,9 @@ func (p *profiler) doRequest(bat batch) error {
 		return err
 	}
 	ctx := context.Background()
-	if p.cfg.uploadTimeout != 0 {
+	// uploadTimeout should always be > 0 (see DefaultUploadTimeout) unless the
+	// user explicitly sets it to 0 or a negative number to disable the timeout.
+	if p.cfg.uploadTimeout > 0 {
 		var cancel func()
 		ctx, cancel = context.WithTimeout(context.Background(), p.cfg.uploadTimeout)
 		defer cancel()