[Refactor] Consolidate SupportsEagle (#36063)

Signed-off-by: Benjamin Chislett <bchislett@nvidia.com>

tests/v1/kv_connector/extract_hidden_states_integration/predictable_llama.py

@@ -13,15 +13,15 @@ import torch
 import torch.nn as nn
 
 from vllm.config import VllmConfig
+from vllm.model_executor.models.interfaces import EagleModelMixin
 from vllm.model_executor.models.llama import LlamaForCausalLM
 from vllm.sequence import IntermediateTensors
 
 
-class PredictableLlamaModel(nn.Module):
+class PredictableLlamaModel(nn.Module, EagleModelMixin):
     def __init__(self, *, vllm_config: VllmConfig, prefix: str = ""):
         super().__init__()
         self.config = vllm_config.model_config.hf_config
-        self.aux_hidden_state_layers = tuple[int, ...]()
 
         # Create minimal embed_tokens for embedding
         from vllm.model_executor.layers.vocab_parallel_embedding import (