Handle unsharded Llama2 model types in conversion script
Author: coreyhu
Pull request: yes

# What does this PR do?

Fixes the unsharded condition to check previously looked-up `num_shards` instead of model type. This is important because multiple model types are uncharded (7B and 7BF)

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Comments:
There's currently two options for unsharded `model_size`, 7B and 7Bf (which I assume represents 7B-chat). While we could alternatively remove the *-Bf options for `model_size`, it seems it's kept for backwards compatibility (line 23). Instead, this PR allows for both 7B and 7B-chat to be treated as unsharded.

The docs for this PR live [here](https://moon-ci-docs.huggingface.co/docs/transformers/pr_27069). All of your documentation changes will be reflected on that endpoint.