[Deprecation] Remove fallbacks for embed_input_ids and embed_multimodal (#30458)

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

vllm/model_executor/models/qwen3_vl.py

@@ -1572,12 +1572,7 @@ class Qwen3VLForConditionalGeneration(
         if multimodal_embeddings is None or len(multimodal_embeddings) == 0:
             return inputs_embeds
 
-        if is_multimodal is None:
-            raise ValueError(
-                "`embed_input_ids` now requires `is_multimodal` arg, "
-                "please update your model runner according to "
-                "https://github.com/vllm-project/vllm/pull/16229."
-            )
+        assert is_multimodal is not None
 
         if self.use_deepstack:
             (