Merge pull request #25351 from Kumataro:fix25073_format_g

core: persistence: output reals as human-friendly expression. #25351

Close #25073
Related https://github.com/opencv/opencv/pull/25087

This patch is need to merge same time with https://github.com/opencv/opencv_contrib/pull/3714

### 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/features2d/misc/java/test/SIFTDescriptorExtractorTest.java

@@ -100,7 +100,7 @@ public class SIFTDescriptorExtractorTest extends OpenCVTestCase {
 
         extractor.write(filename);
 
-        String truth = "%YAML:1.0\n---\nname: \"Feature2D.SIFT\"\nnfeatures: 0\nnOctaveLayers: 3\ncontrastThreshold: 4.0000000000000001e-02\nedgeThreshold: 10.\nsigma: 1.6000000000000001e+00\ndescriptorType: 5\n";
+        String truth = "%YAML:1.0\n---\nname: \"Feature2D.SIFT\"\nnfeatures: 0\nnOctaveLayers: 3\ncontrastThreshold: 0.040000000000000001\nedgeThreshold: 10.\nsigma: 1.6000000000000001\ndescriptorType: 5\n";
         String actual = readFile(filename);
         actual = actual.replaceAll("e([+-])0(\\d\\d)", "e$1$2"); // NOTE: workaround for different platforms double representation
         assertEquals(truth, actual);