Merge pull request #25771 from fengyuentau:vittrack_black_input

video: fix vittrack in the case where crop size grows until out-of-memory when the input is black #25771

Fixes https://github.com/opencv/opencv/issues/25760

### Pull Request Readiness Checklist

See details at https://github.com/opencv/opencv/wiki/How_to_contribute#making-a-good-pull-request

- [x] I agree to contribute to the project under Apache 2 License.
- [x] To the best of my knowledge, the proposed patch is not based on a code under GPL or another license that is incompatible with OpenCV
- [x] The PR is proposed to the proper branch
- [x] There is a reference to the original bug report and related work
- [x] There is accuracy test, performance test and test data in opencv_extra repository, if applicable
      Patch to opencv_extra has the same branch name.
- [x] The feature is well documented and sample code can be built with the project CMake

modules/video/include/opencv2/video/tracking.hpp

@@ -920,6 +920,7 @@ public:
         CV_PROP_RW int target;
         CV_PROP_RW Scalar meanvalue;
         CV_PROP_RW Scalar stdvalue;
+        CV_PROP_RW float tracking_score_threshold;
     };
 
     /** @brief Constructor