Dangling HTTP/3 connection after client has been stopped

**Jetty version(s)**
12.1.11

**HTTP version**
All

**Java version/vendor**
17 (Temurin)

**OS type/version**
Mac OS

**Description**
There are dangling connections being reported on Jetty server side even after the only connected Jetty client has been closed

**How to reproduce?**
The code in https://github.com/kwin/jetty-connectionhandling contains some simple tests in https://github.com/kwin/jetty-connectionhandling/blob/main/src/test/java/org/example/jetty/HttpClientTest.java which connects a Jetty HTTP Client to a Jetty HTTP server (both running in the same VM) via different HTTP versions and checks the lingering connections afterwards on server side.

The HTTP3 client test fails due to one non-closed connection after the Jetty client has been stopped.

Start with the reproduction tests in src/test/java/org/example/jetty/HttpClientTest.java from the linked jetty-connectionhandling repository, focusing on the HTTP/3 client case and how it stops the client. Compare the server-side connection state before and after stopping. Done means the HTTP/3 test no longer reports a dangling connection.

Written by the indexing model from the issue text.