Publishers / subscribers are never closed when connection closes

[Raphtor]

Describe the bug
If I connect to the endpoint via the Unity player, create subscribers/publishers, and then close the connection (i.e by stopping Unity), the subscribers/publishers are never destroyed and remain in the list of ros2 topic list and ros2 node list.

To Reproduce
Steps to reproduce the behavior:

1. Launch Unity
2. Launch docker container with endpoint
3. Click play in Unity with scripts that register publishers/subscribers
4. ros2 topic list and ros2 node list show correct subscribers/publishers
5. Stop Unity editor execution
6. ros2 topic list and ros2 node list still show subscribers/publishers, despite the log message
   [INFO] [1649729856.926835838] [UnityEndpoint]: Disconnected from 172.17.0.1

Console logs / stack traces
Docker container endpoint

root@0c49719e8970:/home/dev_ws# ros2 run ros_tcp_endpoint default_server_endpoint --ros-args -p ROS_IP:=0.0.0.0
[INFO] [1649731919.301293293] [UnityEndpoint]: Starting server on 0.0.0.0:10000
[INFO] [1649731924.108205420] [UnityEndpoint]: Connection from 172.17.0.1
[INFO] [1649731924.260963087] [UnityEndpoint]: RegisterSubscriber(/cmd_vel, <class 'geometry_msgs.msg._twist.Twist'>) OK
[INFO] [1649731924.278215629] [UnityEndpoint]: RegisterSubscriber(/tf, <class 'tf2_msgs.msg._tf_message.TFMessage'>) OK
[INFO] [1649731924.287839920] [UnityEndpoint]: RegisterPublisher(/cmd_vel, <class 'geometry_msgs.msg._twist.Twist'>) OK
[INFO] [1649731924.302599337] [UnityEndpoint]: RegisterPublisher(/pose_stamped, <class 'geometry_msgs.msg._pose_stamped.PoseStamped'>) OK
[WARN] [1649731924.304394170] [rcl.logging_rosout]: Publisher already registered for provided node name. If this is due to multiple nodes with the same name then all logs for that logger name will go out over the existing publisher. As soon as any node with that name is destructed it will unregister the publisher, preventing any further logs for that name from being published on the rosout topic.
[INFO] [1649731924.319359004] [UnityEndpoint]: RegisterPublisher(/cmd_vel, <class 'geometry_msgs.msg._twist.Twist'>) OK
[WARN] [1649731924.321670712] [rcl.logging_rosout]: Publisher already registered for provided node name. If this is due to multiple nodes with the same name then all logs for that logger name will go out over the existing publisher. As soon as any node with that name is destructed it will unregister the publisher, preventing any further logs for that name from being published on the rosout topic.
[INFO] [1649731924.341157712] [UnityEndpoint]: RegisterPublisher(/pose_stamped, <class 'geometry_msgs.msg._pose_stamped.PoseStamped'>) OK
[ERROR] [1649731932.677630258] [UnityEndpoint]: Exception: No more data available
[INFO] [1649731932.679670758] [UnityEndpoint]: Disconnected from 172.17.0.1

Environment (please complete the following information, where applicable):

• Unity Version: [e.g. Unity 2021.2.19f1]
• Unity machine OS + version: Mac Montery (M1)
• ROS machine OS + version: Ubuntu 20.04 Foxy
• ROS–Unity communication: Docker
• Branch or version: 0.7.0