fix: adding previously created PrivateEndpoint network parameter in Model deploy helper method

PiperOrigin-RevId: 521809909

Author: vertex-sdk-bot

google/cloud/aiplatform/models.py

@@ -3464,7 +3464,7 @@ def _deploy(
             endpoint.resource_name,
             self,
             endpoint._gca_resource.traffic_split,
-            network=network,
+            network=network or endpoint.network,
             deployed_model_display_name=deployed_model_display_name,
             traffic_percentage=traffic_percentage,
             traffic_split=traffic_split,