[Bugfix] Fix layer skip logic with bitsandbytes

[mgoin]

Found while debugging why openbmb/MiniCPM-Llama3-V-2_5-int4 doesn't work in #6932, however this is not the full solution.

The current implementation was doing a substring match, which causes kv_proj to match within qkv_proj. We want to match exact module names between the "dots" in full module names.

References for llm_int8_skip_modules:

• https://huggingface.co/openbmb/MiniCPM-Llama3-V-2_5-int4/blob/028d758be0c431f9cf79c859b7124e12aaed5129/config.json#L39-L43
• https://huggingface.co/Isotr0py/Llama-3.2-11B-Vision-Instruct-bnb-8bit/blob/93905aff4669cc350692a99561f68c535ce0c7d9/config.json#L17-L20

[github-actions]

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[DarkLight1337]

LGTM