Change default max_output_tokens to None and add comprehensive model tests (#9366)

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

openhands/memory/memory.py

@@ -296,7 +296,6 @@ class Memory:
                 self.knowledge_microagents[name] = agent_knowledge
             for name, agent_repo in repo_agents.items():
                 self.repo_microagents[name] = agent_repo
-
         except Exception as e:
             logger.warning(
                 f'Failed to load user microagents from {USER_MICROAGENTS_DIR}: {str(e)}'