[Model] Re-add the implicit conversion feature for as_seq_cls_model (#21103)

Signed-off-by: wang.yuqi <noooop@126.com>

vllm/model_executor/models/qwen3.py

@@ -44,7 +44,6 @@ from vllm.model_executor.layers.vocab_parallel_embedding import ParallelLMHead
 from vllm.model_executor.sampling_metadata import SamplingMetadata
 from vllm.sequence import IntermediateTensors
 
-from .adapters import as_seq_cls_model
 from .interfaces import SupportsLoRA, SupportsPP
 from .qwen2 import Qwen2MLP as Qwen3MLP
 from .qwen2 import Qwen2Model
@@ -320,6 +319,3 @@ class Qwen3ForCausalLM(nn.Module, SupportsLoRA, SupportsPP):
                            if self.config.tie_word_embeddings else None),
         )
         return loader.load_weights(weights)
-
-
-Qwen3ForSequenceClassification = as_seq_cls_model(Qwen3ForCausalLM)