Fix padding value in rec model, and box sort in det model (#8552)

deploy/cpp_infer/src/preprocess_op.cpp

@@ -112,7 +112,7 @@ void CrnnResizeImg::Run(const cv::Mat &img, cv::Mat &resize_img, float wh_ratio,
              cv::INTER_LINEAR);
   cv::copyMakeBorder(resize_img, resize_img, 0, 0, 0,
                      int(imgW - resize_img.cols), cv::BORDER_CONSTANT,
-                     {127, 127, 127});
+                     {0, 0, 0});
 }
 
 void ClsResizeImg::Run(const cv::Mat &img, cv::Mat &resize_img,