Update QAT recipe to match full finetune recipe (5/12/25)

**Summary:** Similar to meta-pytorch#1854. Update `qat_distributed` recipe to mirror `full_finetune_distributed` up until a6db644. The new major feature that is excluded from `qat_distributed` is FP8 finetuning (meta-pytorch#2546), since QAT FP8 is not supported in torchao yet.

Diff between full finetune and QAT recipes: P1809370361
```
diff --color recipes/full_finetune_distributed.py recipes/qat_distributed.py
```

**Test Plan:**

Finetune:
```
tune run --nnodes 1 --nproc_per_node 4 qat_distributed --config llama3_2/3B_qat_full \
    epochs=1 \
    batch_size=16 \
    dataset._component_=torchtune.datasets.alpaca_cleaned_dataset \
    checkpointer.output_dir=/home/andrewor/local/logs/tune/Llama3.2-3B_alpaca_qat \
    output_dir=/home/andrewor/local/logs/tune/Llama3.2-3B_alpaca_qat/metrics \
    metric_logger.log_dir=/home/andrewor/local/logs/tune/Llama3.2-3B_alpaca_qat/metrics \
    quantizer._component_=torchtune.training.quantization.Int8DynActInt4WeightQATQuantizer \
    quantizer.groupsize=32
```

Quantize:
```
tune run quantize --config quantization \
    model._component_=torchtune.models.llama3_2.llama3_2_3b \
    checkpointer._component_=torchtune.training.FullModelHFCheckpointer \
    checkpointer.checkpoint_dir=/home/andrewor/local/logs/tune/Llama3.2-3B_alpaca_qat/epoch_0 \
    checkpointer.output_dir=/home/andrewor/local/logs/tune/Llama3.2-3B_alpaca_qat/epoch_0_out \
    'checkpointer.checkpoint_files=[model-00001-of-00002.safetensors,model-00002-of-00002.safetensors]' \
    checkpointer.model_type=LLAMA3 \
    quantizer._component_=torchtune.training.quantization.Int8DynActInt4WeightQuantizer \
    quantizer.groupsize=32
```

Eval:
```
tune run eleuther_eval --config eleuther_evaluation \
    batch_size=1 \
    'tasks=[wikitext]' \
    model._component_=torchtune.models.llama3_2.llama3_2_3b \
    checkpointer._component_=torchtune.training.FullModelTorchTuneCheckpointer \
    checkpointer.checkpoint_dir=/home/andrewor/local/logs/tune/Llama3.2-3B_alpaca_qat/epoch_0 \
    checkpointer.output_dir=/home/andrewor/local/logs/tune/Llama3.2-3B_alpaca_qat/epoch_0_out \
    'checkpointer.checkpoint_files=[model-00001-of-00002-8da4w.ckpt]' \
    checkpointer.model_type=LLAMA3 \
    tokenizer._component_=torchtune.models.llama3.llama3_tokenizer \
    tokenizer.path=/tmp/Meta-Llama-3-8B-Instruct/original/tokenizer.model \
    quantizer._component_=torchtune.training.quantization.Int8DynActInt4WeightQuantizer \
    quantizer.groupsize=32
```

Results:
```
experiment_name          tok/s                peak_mem_active    peak_mem_alloc    peak_mem_reserved
-----------------------  -------------------  -----------------  ----------------  -------------------
Llama3.2-3B_alpaca_full  4677.163 (+0.000%)   12.261 (+0.000%)   12.261 (+0.000%)  15.778 (+0.000%)
Llama3.2-3B_alpaca_qat   1873.316 (-59.948%)  13.047 (+6.409%)   13.047 (+6.409%)  17.226 (+9.176%)

experiment_name          hellaswag_acc                   wikitext_word_perplexity
-----------------------  ------------------------------  -------------------------------
Llama3.2-3B_alpaca_full  0.470 quant, 0.534 float        18.563 quant, 12.364 float
Llama3.2-3B_alpaca_qat   0.511 quant, recovered 63.043%  13.792 quant, recovered 76.962%
```

Author: andrewor14