Merge pull request #27366 from chacha21:arrowedLine_clipped

Try to fix distant points to save time when ThickLine() calls FillConvexPoly() #27366

Proposal for #27365

cv::clipLine() is useful, but one should take care of a margin to preserve line caps.

### 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
- [ ] There is accuracy test, performance test and test data in opencv_extra repository, if applicable
      Patch to opencv_extra has the same branch name.
- [ ] The feature is well documented and sample code can be built with the project CMake

modules/imgproc/test/test_drawing.cpp

@@ -589,7 +589,7 @@ TEST(Drawing, longline)
     Mat mat = Mat::zeros(256, 256, CV_8UC1);
 
     line(mat, cv::Point(34, 204), cv::Point(46400, 47400), cv::Scalar(255), 3);
-    EXPECT_EQ(310, cv::countNonZero(mat));
+    EXPECT_EQ(264, cv::countNonZero(mat));
 
     Point pt[6];
     pt[0].x = 32;