[BUG] offloading section in config file never carried to autotuner

Describe the bug
I tried to enable offloading in the zero2_auto.json file with the following lines,

  "zero_optimization": {
    "stage": 2,
    "offload_optimizer": {
        "device": "cpu",
        "pin_memory": true
    },
    ...
  }

It works fine for normal runs without the --autotune flag. However, once I use deepspeed --autotune, none of the automatically generated .json files have the offload_optimizer section, i.e. one sample json file generated by autotuner

This contradicts what is stated in the README: "Currently, the DeepSpeed Autotuner does not tune offloading behaviors but instead uses the values defined in the offload section of the DeepSpeed configuration file." [https://github.com/microsoft/DeepSpeed/tree/master/deepspeed/autotuning#offloading-and-nvme]

To Reproduce

git clone https://github.com/cxxz/llama_deepspeed_autotune.git
cd llama_deepspeed_autotune
./run_autotune_llama_4A100.sh

Expected behavior
All generated ds_config.json during the search should have the offload section.

System info (please complete the following information):

• Python version: 3.10
• DeepSpeed version: 0.9.1