[V1][Spec Dec Bug Fix] Respect Spec Dec Method Specification (#16636)

Signed-off-by: Bryan Lu <[email protected]>

Author: luyuzhe111

vllm/config.py

@@ -2341,7 +2341,9 @@ def __post_init__(self):
                 )
 
                 # Automatically detect the method
-                if "eagle-" in self.draft_model_config.model.lower():
+                if self.method == 'eagle':
+                    pass
+                elif "eagle-" in self.draft_model_config.model.lower():
                     self.method = "eagle"
                 elif self.draft_model_config.hf_config.model_type == "medusa":
                     self.method = "medusa"