tests(cross-runtime-serde): hide torch-trt DLLs on Windows too

[tp5uiuc]

Description

tests/py/dynamo/models/_cross_runtime_load_helper.py:_hide_so_files() only globbed the
Linux/macOS-style libtorchtrt* pattern. On Windows the Torch-TensorRT runtime libraries
are named torchtrt.dll / torchtrt_runtime.dll (no lib prefix; see
py/torch_tensorrt/_features.py), so the glob returned an empty list and the spawned
Python-only subprocess kept torch_tensorrt_runtime == True, tripping the
C++ runtime should be disabled assertion.

Make the glob platform-aware:

• Windows: torchtrt*.dll, torchtrt*.lib
• Linux/macOS: libtorchtrt* (unchanged)

Fixes the three test_cross_runtime_serde.py failures on the Windows L2 dynamo compile
runners surfaced in #4330:

• test_save_cpp_load_python
• test_save_python_load_python
• test_save_python_load_cpp

Type of change

• Bug fix (test-only; no runtime API change)

Checklist:

• My code follows the style guidelines of this project (You can use the linters)
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas and hacks
• I have made corresponding changes to the documentation
• I have added tests to verify my fix or my feature
• New and existing unit tests pass locally with my changes
• I have added the relevant labels to my PR in so that relevant reviewers are notified

[cehongwang]

LGTM

[tp5uiuc]

[by Claude Code] CI analysis: all red checks on the current run are pre-existing/infra failures, none caused by this 1-file test-helper change.

• L0 dynamo core (cu130/cu132): 10× runtime/test_000_runtime_cache.py failures (AttributeError: 'NoneType' has no attribute 'context', missing runtime_cache.bin). Unrelated test-bed.
• Python-only dynamo runtime (cu130/cu132 + RTX variants): 3× test_004_weight_streaming.py budget assertions. Listed as pre-existing in this PR's README.
• L0 dynamo converter (cu130/cu132): 5× test_cumsum_aten.py — TensorRT build_serialized_network returned None. Listed as pre-existing in this PR's README.
• L0 core python (Windows, cu130): flashinfer-python wheel build fails on Windows. Third-party dep, unrelated.
• L0 torchscript (cu130/cu132): 2h0m20s timeouts. Infra.
• Python-only build Linux aarch64 cu132: pip install torch --pre from download.pytorch.org failed (urllib3). Network/infra.

Counts where visible: 3/68 (python-only dynamo runtime), 5/1977 (dynamo converter), 10/19 (dynamo core). All builds pass (Linux x86_64, Windows, SBSA, Jetpack, RTX). Linters + CLA pass.

Caveat: test_cross_runtime_serde.py lives in tests/py/dynamo/models/, which is not exercised by any L0 job here — it runs only under L2-dynamo-compile-tests (build-test-windows.yml), gated on the Force All Tests[L0+L1+L2] label. Label just applied; awaiting that run as the canonical verifier.

[tp5uiuc]

Let me merge this one in, the $/! for rerunning L2 for a one-line change is questionable. We can confirm from post-merge runs.