[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/gemma.py

@@ -43,7 +43,6 @@ from vllm.model_executor.model_loader.weight_utils import default_weight_loader
 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, is_pp_missing_parameter,
                     make_empty_intermediate_tensors_factory, make_layers,
@@ -426,6 +425,3 @@ class GemmaForCausalLM(nn.Module, SupportsLoRA, SupportsPP):
                            if self.config.tie_word_embeddings else None),
         )
         return loader.load_weights(weights)
-
-
-GemmaForSequenceClassification = as_seq_cls_model(GemmaForCausalLM)