chore: Remove unnecessary check tool type and tool attribute

tool in config.tools cann't be ToolDict and must have computer_use attr

PiperOrigin-RevId: 816283438

Author: seanzhougoogle

src/google/adk/models/google_llm.py

@@ -313,11 +313,7 @@ async def _preprocess_request(self, llm_request: LlmRequest) -> None:
     if llm_request.config and llm_request.config.tools:
       # Check if computer use is configured
       for tool in llm_request.config.tools:
-        if (
-            isinstance(tool, (types.Tool, types.ToolDict))
-            and hasattr(tool, 'computer_use')
-            and tool.computer_use
-        ):
+        if isinstance(tool, types.Tool) and tool.computer_use:
           llm_request.config.system_instruction = None
           await self._adapt_computer_use_tool(llm_request)