Fix: filter builtin llm factories. (#11163)

### Type of change

- [x] Bug Fix (non-breaking change which fixes an issue)

api/apps/llm_app.py

@@ -33,7 +33,7 @@ from rag.llm import EmbeddingModel, ChatModel, RerankModel, CvModel, TTSModel
 def factories():
     try:
         fac = get_allowed_llm_factories()
-        fac = [f.to_dict() for f in fac if f.name not in ["Youdao", "FastEmbed", "BAAI"]]
+        fac = [f.to_dict() for f in fac if f.name not in ["Youdao", "FastEmbed", "BAAI", "Builtin"]]
         llms = LLMService.get_all()
         mdl_types = {}
         for m in llms: