Merge pull request #28907 from chacha21:more_autobuffer

More use of AutoBuffer #28907

When possible, AutoBuffer should be faster than std::vector<>, and should not be worse if it requires a heap allocation rather than a stack allocation.

### 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
- [ ] 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.
- [ ] The feature is well documented and sample code can be built with the project CMake

modules/flann/include/opencv2/flann/ground_truth.h

@@ -47,8 +47,8 @@ void find_nearest(const Matrix<typename Distance::ElementType>& dataset, typenam
     typedef typename Distance::ResultType DistanceType;
     int n = nn + skip;
 
-    std::vector<int> match(n);
-    std::vector<DistanceType> dists(n);
+    cv::AutoBuffer<int> match(n);
+    cv::AutoBuffer<DistanceType> dists(n);
 
     dists[0] = distance(dataset[0], query, dataset.cols);
     match[0] = 0;

modules/flann/include/opencv2/flann/hierarchical_clustering_index.h

@@ -686,8 +686,8 @@ private:
             return;
         }
 
-        std::vector<int> centers(branching);
-        std::vector<int> labels(indices_length);
+        cv::AutoBuffer<int> centers(branching);
+        cv::AutoBuffer<int> labels(indices_length);
 
         int centers_length;
         (this->*chooseCenters)(branching, dsindices, indices_length, &centers[0], centers_length);

modules/flann/include/opencv2/flann/index_testing.h

@@ -99,8 +99,8 @@ float search_with_ground_truth(NNIndex<Distance>& index, const Matrix<typename D
     KNNResultSet<DistanceType> resultSet(nn+skipMatches);
     SearchParams searchParams(checks);
 
-    std::vector<int> indices(nn+skipMatches);
-    std::vector<DistanceType> dists(nn+skipMatches);
+    cv::AutoBuffer<int> indices(nn+skipMatches);
+    cv::AutoBuffer<DistanceType> dists(nn+skipMatches);
     int* neighbors = &indices[skipMatches];
 
     int correct = 0;

modules/flann/include/opencv2/flann/lsh_table.h

@@ -490,7 +490,7 @@ inline LshStats LshTable<unsigned char>::getStats() const
          != end; )
         if (*iterator < bin_end) {
             if (is_new_bin) {
-                stats.size_histogram_.push_back(std::vector<unsigned int>(3, 0));
+                stats.size_histogram_.emplace_back(3, 0);
                 stats.size_histogram_.back()[0] = bin_start;
                 stats.size_histogram_.back()[1] = bin_end - 1;
                 is_new_bin = false;