Closing of SSE streams has changed

[edwig]

With the new HTML-5 standard of 2023 the closing of a SSE event stream has changed.
Clients no longer listen for the "event:close" to close the stream.

see the following link to the current WHATWG standardization:
https://html.spec.whatwg.org/multipage/server-sent-events.html#event-stream-interpretation

"Clients will reconnect if the connection is closed; a client can be told to stop reconnecting using the HTTP 204 No Content response code."