Revert "Add flashinfer rmsnorm + quant fusion support SM90, SM100, SM120"

[Fridge003]

Reverts #32994

This commit breaks CI: https://github.com/sgl-project/sglang/actions/runs/30868463119/job/91865475888

---

CI States

Latest PR Test (Base): ⏳ Run #30870646431
Latest PR Test (Extra): ⏳ Run #30870646307

[gemini-code-assist]

Caution

The consumer version of Gemini Code Assist on GitHub has been sunset. All code review activity has officially ceased.

[DevashishLal-CB]

@hnyls2002 this CI run https://github.com/sgl-project/sglang/actions/runs/30868463119/job/91865475888 didn't build the latest sgl-kernel, the assert that was hit should not even trigger on the latest kernel as I had modified it https://github.com/sgl-project/sglang/pull/32994/changes#diff-05fba125f0fda254854fe7de03d2e1b534b8948809fe696a7a90e84945f33317L1118

Test passed locally on my branch

➜ pytest -v ./test/registered/quant/test_modelopt_fp8.py
=============================================================================== test session starts ===============================================================================
platform linux -- Python 3.12.13, pytest-9.1.1, pluggy-1.6.0 -- /home/devcode/uv_env/sglang/bin/python3
cachedir: .pytest_cache
rootdir: /data/users/devcode/gitrepos/sglang/test
configfile: pytest.ini
plugins: anyio-4.14.2, cov-7.1.0
collected 2 items

test/registered/quant/test_modelopt_fp8.py::TestModeloptFP8::test_gsm8k PASSED                                                                                              [ 50%]
test/registered/quant/test_modelopt_fp8.py::TestModeloptFP8WithRustServer::test_gsm8k SKIPPED (embedded rust server extension not built)                                    [100%]

================================================================================ warnings summary =================================================================================
../../../../../home/devcode/uv_env/sglang/lib64/python3.12/site-packages/_pytest/config/__init__.py:1464
  /home/devcode/uv_env/sglang/lib64/python3.12/site-packages/_pytest/config/__init__.py:1464: PytestConfigWarning: Unknown config option: asyncio_mode

    self._warn_or_fail_if_strict(f"Unknown config option: {key}\n")

../../../../../home/devcode/uv_env/sglang/lib64/python3.12/site-packages/torch/jit/_script.py:365: 14 warnings
  /home/devcode/uv_env/sglang/lib64/python3.12/site-packages/torch/jit/_script.py:365: DeprecationWarning: `torch.jit.script_method` is deprecated. Please switch to `torch.compile` or `torch.export`.
    warnings.warn(

-- Docs: https://docs.pytest.org/en/stable/how-to/capture-warnings.html
============================================================== 1 passed, 1 skipped, 15 warnings in 152.75s (0:02:32) =============================================================