[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/qwen2.py

@@ -50,7 +50,6 @@ from vllm.model_executor.model_loader.weight_utils import (
 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 .utils import (AutoWeightsLoader, PPMissingLayer, extract_layer_index,
                     is_pp_missing_parameter,
@@ -496,6 +495,3 @@ class Qwen2ForCausalLM(nn.Module, SupportsLoRA, SupportsPP):
                            if self.config.tie_word_embeddings else None),
         )
         return loader.load_weights(weights)
-
-
-Qwen2ForSequenceClassification = as_seq_cls_model(Qwen2ForCausalLM)