[Refactor, Fix]: Agent controller state/metrics management (#9012)

Co-authored-by: openhands <openhands@all-hands.dev>

openhands/llm/llm.py

@@ -773,9 +773,6 @@ class LLM(RetryMixin, DebugMixin):
     def __repr__(self) -> str:
         return str(self)
 
-    def reset(self) -> None:
-        self.metrics.reset()
-
     def format_messages_for_llm(self, messages: Message | list[Message]) -> list[dict]:
         if isinstance(messages, Message):
             messages = [messages]