test_transformer_engine_executor.py is not runnable in the PyTorch build without distributed support

Nobody has claimed this yet.

## 🐛 Bug

1. Modify `is_available()` function to return False in `torch/distributed/__init__.py`
2. Modify `is_available()` function to return False in `torch/distributed/rpc/__init__.py`
3. Run `pytest thunder/tests/test_transformer_engine_executor.py --collect-only`
```py
=============================================================================================== ERRORS ===============================================================================================
_________________________________________________________________ ERROR collecting thunder/tests/test_transformer_engine_executor.py _________________________________________________________________
ImportError while importing test module '/opt/pytorch/lightning-thunder/thunder/tests/test_transformer_engine_executor.py'.
Hint: make sure your test modules/packages have valid Python names.
Traceback:
/usr/lib/python3.12/importlib/__init__.py:90: in import_module
return _bootstrap._gcd_import(name[level:], package, level)
thunder/tests/test_transformer_engine_executor.py:13: in
import transformer_engine.pytorch as te
/usr/local/lib/python3.12/dist-packages/transformer_engine/pytorch/__init__.py:64: in
from transformer_engine.pytorch.module import LayerNormLinear
/usr/local/lib/python3.12/dist-packages/transformer_engine/pytorch/module/__init__.py:6: in
from .layernorm_linear import LayerNormLinear
/usr/local/lib/python3.12/dist-packages/transformer_engine/pytorch/module/layernorm_linear.py:15: in
from .base import (
/usr/local/lib/python3.12/dist-packages/transformer_engine/pytorch/module/base.py:28: in
from ..distributed import (
/usr/local/lib/python3.12/dist-packages/transformer_engine/pytorch/distributed.py:16: in
from torch.distributed.fsdp import FullyShardedDataParallel as FSDP
/usr/local/lib/python3.12/dist-packages/torch/distributed/fsdp/__init__.py:1: in
from ._flat_param import FlatParameter as FlatParameter
/usr/local/lib/python3.12/dist-packages/torch/distributed/fsdp/_flat_param.py:45: in
from torch.testing._internal.distributed.fake_pg import FakeProcessGroup
/usr/local/lib/python3.12/dist-packages/torch/testing/_internal/distributed/fake_pg.py:5: in
from torch._C._distributed_c10d import (
E ModuleNotFoundError: No module named 'torch._C._distributed_c10d'; 'torch._C' is not a package
_________________________________________________________________ ERROR collecting thunder/tests/test_transformer_engine_executor.py _________________________________________________________________
ImportError while importing test module '/opt/pytorch/lightning-thunder/thunder/tests/test_transformer_engine_executor.py'.
Hint: make sure your test modules/packages have valid Python names.
Traceback:
/usr/lib/python3.12/importlib/__init__.py:90: in import_module
return _bootstrap._gcd_import(name[level:], package, level)
thunder/tests/test_transformer_engine_executor.py:13: in
import transformer_engine.pytorch as te
/usr/local/lib/python3.12/dist-packages/transformer_engine/pytorch/__init__.py:64: in
from transformer_engine.pytorch.module import LayerNormLinear
/usr/local/lib/python3.12/dist-packages/transformer_engine/pytorch/module/__init__.py:6: in
from .layernorm_linear import LayerNormLinear
/usr/local/lib/python3.12/dist-packages/transformer_engine/pytorch/module/layernorm_linear.py:15: in
from .base import (
/usr/local/lib/python3.12/dist-packages/transformer_engine/pytorch/module/base.py:28: in
from ..distributed import (
/usr/local/lib/python3.12/dist-packages/transformer_engine/pytorch/distributed.py:16: in
from torch.distributed.fsdp import FullyShardedDataParallel as FSDP
/usr/local/lib/python3.12/dist-packages/torch/distributed/fsdp/__init__.py:1: in
from ._flat_param import FlatParameter as FlatParameter
/usr/local/lib/python3.12/dist-packages/torch/distributed/fsdp/_flat_param.py:45: in
from torch.testing._internal.distributed.fake_pg import FakeProcessGroup
/usr/local/lib/python3.12/dist-packages/torch/testing/_internal/distributed/fake_pg.py:5: in
from torch._C._distributed_c10d import (
E ModuleNotFoundError: No module named 'torch._C._distributed_c10d'; 'torch._C' is not a package
====================================================================================== short test summary info =======================================================================================
ERROR thunder/tests/test_transformer_engine_executor.py
ERROR thunder/tests/test_transformer_engine_executor.py
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! Interrupted: 2 errors during collection !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
=============================================================================== no tests collected, 2 errors in 1.46s ================================================================================
```

cc @borda

Start by running `pytest thunder/tests/test_transformer_engine_executor.py --collect-only` and inspect the import at line 13 of `thunder/tests/test_transformer_engine_executor.py`. Reproduce the failure with distributed support unavailable, then trace the imports through `torch/distributed/__init__.py` and `torch/distributed/rpc/__init__.py`; done means collection completes without the reported import errors.

Written by the indexing model from the issue text.