[Model] Always use Transformers backend for PaliGemma and Gemma3-MM (#26715)

Signed-off-by: DarkLight1337 <tlleungac@connect.ust.hk>

examples/offline_inference/vision_language.py

@@ -248,7 +248,8 @@ def run_gemma3(questions: list[str], modality: str) -> ModelRequestData:
         model=model_name,
         max_model_len=2048,
         max_num_seqs=2,
-        mm_processor_kwargs={"do_pan_and_scan": True},
+        # TODO: Support this in transformers backend
+        # mm_processor_kwargs={"do_pan_and_scan": True},
         limit_mm_per_prompt={modality: 1},
     )