add gateway cluster deletion after gateway tests

tox.ini

@@ -772,6 +772,11 @@ commands =
     bash -c " source ./scripts/get_k8s_secret_ci.sh; \
     pytest tests/integration/network -k 'not test_domain_gateway_user_code' -p no:randomly -vvvv"
 
+    # Shutting down the gateway cluster to free up space, as the
+    # below code does not require gateway cluster
+    bash -c "k3d cluster delete testgateway1 || true"
+    bash -c "docker volume rm k3d-testgateway1-images --force || true"
+
     ; ; container workload
     ; bash -c 'if [[ "$PYTEST_MODULES" == *"container_workload"* ]]; then \
     ;     echo "Starting Container Workload test"; date; \