Merge pull request #24808 from fengyuentau:fix_layernorm

dnn: no layer norm fusion if axes.back() is not the axis of last dimension #24808

Merge with https://github.com/opencv/opencv_extra/pull/1137

Resolves https://github.com/opencv/opencv/issues/24797

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

modules/dnn/test/test_graph_simplifier.cpp

@@ -47,6 +47,10 @@ TEST_F(Test_Graph_Simplifier, LayerNormSubGraph) {
     test("layer_norm_expanded_with_initializers", "LayerNormalization");
 }
 
+TEST_F(Test_Graph_Simplifier, LayerNormNoFusionSubGraph) {
+    test("layer_norm_no_fusion", std::vector<std::string>{"NaryEltwise", "Reduce", "Sqrt"});
+}
+
 TEST_F(Test_Graph_Simplifier, ResizeSubgraph) {
     /* Test for 6 subgraphs:
         - GatherCastSubgraph