Merge pull request #26849 from sturkmen72:apng-writeanimation

APNG encoding optimization #26849

related #26840

### 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/imgcodecs/perf/perf_decode_encode.cpp

@@ -101,7 +101,7 @@ PERF_TEST_P(Encode, bgr, testing::ValuesIn(exts))
 
     TEST_CYCLE() imencode(GetParam(), src, buf);
 
-    std::cout << "Encoded buffer size: " << buf.size()
+    std::cout << "  Encoded buffer size: " << buf.size()
         << " bytes, Compression ratio: " << std::fixed << std::setprecision(2)
         << (static_cast<double>(buf.size()) / (src.total() * src.channels())) * 100.0 << "%" << std::endl;
 
@@ -120,7 +120,7 @@ PERF_TEST_P(Encode, multi, testing::ValuesIn(exts_multi))
 
     TEST_CYCLE() imencode(GetParam(), vec, buf);
 
-    std::cout << "Encoded buffer size: " << buf.size()
+    std::cout << "  Encoded buffer size: " << buf.size()
         << " bytes, Compression ratio: " << std::fixed << std::setprecision(2)
         << (static_cast<double>(buf.size()) / (vec[0].total() * vec[0].channels())) * 100.0 << "%" << std::endl;