refactor: remove triggered_by field from webhook triggers and use automatic sync

- Remove triggered_by field from WorkflowWebhookTrigger model
- Replace manual webhook creation/deletion APIs with automatic sync via WebhookService
- Keep only GET API for retrieving webhook information
- Use same webhook ID for both debug and production environments (differentiated by endpoint)
- Add sync_webhook_relationships to automatically manage webhook lifecycle
- Update tests to remove triggered_by references
- Clean up unused imports and fix type checking issues

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

api/tests/test_containers_integration_tests/services/test_webhook_service.py

@@ -130,7 +130,7 @@ class TestWebhookService:
             node_id="webhook_node",
             tenant_id=tenant.id,
             webhook_id=webhook_id,
-            triggered_by="production",
+            created_by=account.id,
         )
         db_session_with_containers.add(webhook_trigger)
         db_session_with_containers.commit()