fix: #981 (#983)

### What does this PR do?

Type of change: Bug fix

<!-- Details about the change. -->

An issue is reported in
#981 where `str(v)` on
some `TransformerConfig` fields will raise `TypeError`. 

We remove the yaml saving logic entirely as it's unused and can cause future errors still.

### Usage

```python
# Add a code snippet demonstrating how to use this
```

### Testing
<!-- Mention how have you tested your change if applicable. -->

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### Additional Information
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<!-- This is an auto-generated comment: release notes by coderabbit.ai
-->
## Summary by CodeRabbit

* **Bug Fixes**
* Improved checkpoint loading stability by handling unusual
configuration values more gracefully; such values no longer cause
failures and are skipped with a warning instead.
* Reduced risk of crashes during configuration processing when
encountering non-standard or unsupported objects.

* **Chores**
* Checkpoints no longer include saved run configuration or tool-version
metadata, yielding smaller, simpler checkpoint files.
<!-- end of auto-generated comment: release notes by coderabbit.ai -->

---------

Signed-off-by: Chenhan Yu <chenhany@nvidia.com>
Signed-off-by: Keval Morabia <28916987+kevalmorabia97@users.noreply.github.com>
Signed-off-by: Asha Anoosheh <aanoosheh@nvidia.com>
Co-authored-by: Keval Morabia <28916987+kevalmorabia97@users.noreply.github.com>
Co-authored-by: coderabbitai[bot] <136622811+coderabbitai[bot]@users.noreply.github.com>
Co-authored-by: Asha Anoosheh <aanoosheh@nvidia.com>

Author: 4 people

modelopt/torch/opt/plugins/mcore_dist_checkpointing.py

@@ -22,7 +22,6 @@
 from typing import Any
 
 import torch
-import yaml
 from megatron.core import dist_checkpointing, mpu
 from megatron.core.dist_checkpointing.serialization import get_default_load_sharded_strategy
 from megatron.core.dist_checkpointing.strategies.common import COMMON_STATE_FNAME
@@ -36,21 +35,6 @@
 
 SUPPORTED_WRAPPERS[Float16Module] = "module"
 
-DROP_SUBSTRINGS = [
-    "fp4",
-    "fp8",
-    "tp_",
-    "parallel",
-    "cuda_graph",
-    "init_",
-    "cpu",
-    "recompute",
-    "inference",
-    "pipeline",
-    "comm",
-    "batch",
-]
-
 
 def remove_per_module_state(
     modelopt_state: dict[str, Any],
@@ -138,29 +122,6 @@ def save_sharded_modelopt_state(
         sharded_strategy: configures sharded tensors saving behavior and backend
         prefix: the prefix to add to the modelopt_state keys ("model." for NeMo)
     """
-
-    def _parse_transformer_config(transformer_config: dict) -> dict:
-        config = {}
-
-        for k, v in transformer_config.items():
-            if any(substring in k for substring in DROP_SUBSTRINGS):
-                continue
-            if isinstance(v, (bool, int, str)):
-                config[k] = v
-            else:
-                config[k] = str(v)
-
-        return config
-
-    # Save own version of run config, if not already saved by the framework.
-    if dist.is_master() and not os.path.exists(f"{checkpoint_name}/run_config.yaml"):
-        run_config_name = f"{checkpoint_name}/modelopt_run_config.yaml"
-        # We avoid deepcopy since some attributes in Megatron-Bridge config cannot be deepcopied.
-        config_dict = _parse_transformer_config(model[0].config.__dict__)
-        config_dict["nvidia_modelopt_version"] = modelopt.__version__
-        with open(run_config_name, "w") as f:
-            yaml.dump(config_dict, f, default_flow_style=False)
-
     if not mto.ModeloptStateManager.is_converted(model[0]):
         return
     if len(model) > 1: