fix(langchain): Add "dont_throw" to "on_llm_end" and remove blank file (#3232)

Author: LuizDMM

packages/opentelemetry-instrumentation-langchain/opentelemetry/instrumentation/langchain/callback_handler.py

@@ -477,6 +477,7 @@ def on_llm_start(
         else:
             set_llm_request(span, serialized, prompts, kwargs, self.spans[run_id])
 
+    @dont_throw
     def on_llm_end(
         self,
         response: LLMResult,