convert : fix RuntimeError when stripping FP8 KV-cache scales (#22818)

convert : fix RuntimeError when stripping FP8 KV-cache scales (#22818)

* convert : fix RuntimeError when stripping FP8 KV-cache scales

In ModelBase._generate_nvfp4_tensors the final cleanup loop iterates
self.model_tensors.keys() and calls del on the same dict, which raises
RuntimeError: dictionary changed size during iteration when a ModelOpt
NVFP4 model also has FP8 KV-cache scales (e.g. mmangkad/Qwen3.6-35B-A3B-NVFP4
and any modelopt config with kv_cache_quant_algo: FP8).

Wrap the keys view in list() so the deletions happen on a snapshot.

* re-add another accidentally removed list

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Co-authored-by: Sigbjørn Skjæret <redacted>