fix: Add vertexai initialization for code being deployed to AgentEngine

Co-authored-by: Yeesian Ng <ysian@google.com>
PiperOrigin-RevId: 832031219

Author: yeesian

src/google/adk/cli/cli_deploy.py

@@ -64,6 +64,8 @@
 """
 
 _AGENT_ENGINE_APP_TEMPLATE: Final[str] = """
+import os
+import vertexai
 from vertexai.agent_engines import AdkApp
 
 if {is_config_agent}:
@@ -78,9 +80,12 @@
   from .agent import {adk_app_object}
 
 if {express_mode}: # Whether or not to use Express Mode
-  import os
-  import vertexai
   vertexai.init(api_key=os.environ.get("GOOGLE_API_KEY"))
+else:
+  vertexai.init(
+    project=os.environ.get("GOOGLE_CLOUD_PROJECT"),
+    location=os.environ.get("GOOGLE_CLOUD_LOCATION"),
+  )
 
 adk_app = AdkApp(
     {adk_app_type}={adk_app_object},