Too many SSE network connections

[gemo12123]

Describe the bug
When I used SSE to connect to the Mcp server, I clicked "reconnect" which caused too many SSE network connections, and I saw a large number of file descriptors on the server. Even if some connections are no longer needed, they will not be released

To Reproduce
Steps to reproduce the behavior:

1. use sse
2. click "reconnect" multiple times

Expected behavior
Release useless connections