Set a timeout on chatserver requests
If there is something wrong with the chatserver (like #1068) and requests take forever, php waits also indefinitely for the requests to be finished, stacking up open requests which led to the outage 2021-03-30.
guzzle (the http request library, that we use) offers a timeout option: https://docs.guzzlephp.org/en/stable/request-options.html#timeout
Related code: https://gitlab.com/foodsharing-dev/foodsharing/-/blob/master/src/Lib/WebSocketConnection.php