inventory_docker_swarm test - Remove exit code from trap (#391)

Setting the exit code in a trap overrides the exit code that caused the
trap to be called. This means if the test failed and called the trap,
the test will exit with 0 rather than the failure exit code.

tests/integration/targets/inventory_docker_swarm/runme.sh

@@ -8,7 +8,6 @@ cleanup() {
     echo "Cleanup"
     ansible-playbook playbooks/swarm_cleanup.yml
     echo "Done"
-    exit 0
 }
 
 trap cleanup INT TERM EXIT