chore: remove unused line for Client()

PiperOrigin-RevId: 781617898

Author: wuliang229

contributing/samples/google_search_agent/agent.py

@@ -14,10 +14,6 @@
 
 from google.adk import Agent
 from google.adk.tools import google_search
-from google.genai import Client
-
-# Only Vertex AI supports image generation for now.
-client = Client()
 
 root_agent = Agent(
     model='gemini-2.0-flash-001',