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## Summary
Fix swizzle / swap_first_dims RTC build and normalization test issues on `release_v2.7` (ROCm/HIP).

## Background
- ROCm/HIP path currently hits build/runtime/test issues in:
  - `swizzle_scaling_factors` (HIP compile constraints with `__device__ __host__` constexpr)
  - RTC `swap_first_dims` source selection
  - `test_normalization` when `use_cudnn` is enabled for LayerNorm/RMSNorm
  - PyTorch L0 unittest environment relying on `PYTHONPATH`

## Changes
1) **qa/L0_pytorch_unittest/test.sh**
   - Export `PYTHONPATH` to include `${TE_PATH}` so tests can import from source tree without reinstalling pytest.
   - Removed explicit `pip3 install pytest==8.2.1` from the script.

2) **tests/cpp/operator/test_normalization.cu**
   - Skip LayerNorm/RMSNorm cases when `use_cudnn` is enabled:
     - `GTEST_SKIP(): CudnnLayerNorm and CudnnRmsNorm are disabled.`
   - Avoids running unsupported/disabled cuDNN normalization paths in this configuration.

3) **transformer_engine/common/CMakeLists.txt**
   - Fix RTC header generation for `swap_first_dims` on ROCm:
     - use `transpose/rtc/swap_first_dims.hip` instead of `.cu`.

4) **transformer_engine/common/swizzle/swizzle.cu**
   - For `__HIP_PLATFORM_AMD__`, replace `constexpr __device__ __host__ int ...` with plain `constexpr int ...`
   - Keeps CUDA path unchanged.
   - Addresses HIP compilation constraints while preserving constants’ values and usage.

## Verification
- [x] Build on 10.16.4.9 rocky_8.6 docker Enviroment
- [x] Run `qa/L0_pytorch_unittest/test.sh`
- [x] Run C++ operator tests related to normalization/swizzle as applicable

## Notes
- Branch synced with latest `origin/release_v2.7` before opening this MR.

See merge request dcutoolkit/deeplearing/TransformerEngine!66