fix: remove unused userinfo_endpoint from GoogleApiToolset OIDC config

The userinfo_endpoint field is never read anywhere in ADK, so this
hardcoded URL had no runtime effect. The OAuth flow only uses the
authorization and token endpoints. Removing it.

Co-authored-by: George Weale <gweale@google.com>
PiperOrigin-RevId: 943396380

Author: GWeale

src/google/adk/tools/google_api_tool/google_api_toolset.py

@@ -143,9 +143,6 @@ def _load_toolset_with_oidc_auth(self) -> OpenAPIToolset:
                 'https://accounts.google.com/o/oauth2/v2/auth'
             ),
             token_endpoint='https://oauth2.googleapis.com/token',
-            userinfo_endpoint=(
-                'https://openidconnect.googleapis.com/v1/userinfo'
-            ),
             revocation_endpoint='https://oauth2.googleapis.com/revoke',
             token_endpoint_auth_methods_supported=[
                 'client_secret_post',