ConfidenceMethodConfig DEPRECATED compatibility problem between r1.21.0 and r1.20.0
**Describe the bug**

Loading models trained with Nemo version `r1.21.0` using Nemo `r1.20.0` codebase fails with the following error:
```
[NeMo E 2023-10-23 16:21:42 common:506] Model instantiation failed!
    Target class:       nemo.collections.asr.models.hybrid_rnnt_ctc_bpe_models.EncDecHybridRNNTCTCBPEModel
    Error(s):   'str' object has no attribute 'temperature'
```
This is due to changes in `nemo/collections/asr/parts/utils/asr_confidence_utils.py` - the newer [version ](https://github.com/NVIDIA/NeMo/blob/c0022aec9c8fedd59458935f0378a775b28d0444/nemo/collections/asr/parts/utils/asr_confidence_utils.py#L93-L120) supports the `str` value `DEPRECATED`: 

**Steps/Code to reproduce bug**

The bug occurs when using Nemo `r1.21.0` and finetuning the model [here](https://catalog.ngc.nvidia.com/orgs/nvidia/teams/nemo/models/stt_multilingual_fastconformer_hybrid_large_pc) using the script `examples/asr/speech_to_text_finetune.py` and the config file `examples/asr/conf/speech_to_text_finetune.yaml` with minor modifications.

**Expected behavior**

The `r1.20.0` codebase should be able to load models trained with `r1.21.0` unless the models differ in ways that simply can't be supported by the old code base.  In the later situation, a meaningful error message should indicate that code base is too old for the model.

**Environment overview (please complete the following information)**

 - Environment location: Bare Metal
 - Method of NeMo install: `python -m pip install 'git+https://github.com/NVIDIA/NeMo.git@r1.21.0#egg=nemo_toolkit[all]'`

**Environment details**

If NVIDIA docker image is used you don't need to specify these.
Otherwise, please provide:
- OS version: Ubuntu 20.04
- PyTorch version: pytorch-lightning 2.0.7
- Python version: Conda Python 3.10.13

**Additional context**

Add any other context about the problem here.
Example: GPU model: NVIDIA A100
