Various Transformers v5 fixes

[hmellor]

• Add an alias for transformers.image_processing_utils_fast in the offline mode test
• Remove the vendored Olmo3 config as mentioned in https://github.com/vllm-project/vllm/pull/24534/changes#r2339434281 because this model has been released in Transformers since v4.57.0
• Fix sliding window configuration error in Qwen1.5 testing model (they set it to 0 instead of None which doesn't actually disable sliding window)
• Stop DeepSeekVL2Config from passing an invalid value to DeepSeekV2Confg (DeepSeekV2 always has MLA but DeepSeekVL2 does not)

[gemini-code-assist]

Code Review

This pull request introduces several changes, including updating aliased module patterns for image processing utilities, handling sliding_window=0 in model configurations by converting it to None, and refactoring Olmo3Config to use the upstream transformers library instead of a custom vLLM implementation. Additionally, a check was added in deepseek_vl2.py to remove kv_lora_rank if its value is None before passing it to DeepseekV2Config. A review comment suggests that modifying the language_config dictionary in-place in deepseek_vl2.py could lead to unexpected side effects and recommends using a copy of the dictionary instead.

[gemini-code-assist]

Modifying the language_config dictionary in-place can lead to unexpected side effects for the caller if they reuse the kwargs dictionary. It's safer to work with a copy of the dictionary to avoid such issues.

Suggested change

	# remove kv_lora_rank if not specified, passing None is prohibited
	if language_config.get("kv_lora_rank") is None:
	language_config.pop("kv_lora_rank", None)
	self.text_config = DeepseekV2Config(**language_config)
	# remove kv_lora_rank if not specified, passing None is prohibited
	language_config_copy = language_config.copy()
	if language_config_copy.get("kv_lora_rank") is None:
	language_config_copy.pop("kv_lora_rank", None)
	self.text_config = DeepseekV2Config(**language_config_copy)