gh-84532: Close the accepted connections in test_reconnect

The test left the server-side connections unclosed, which regrtest reported
as an altered environment (ResourceWarning: unclosed socket).

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Author: serhiy-storchaka

Lib/test/test_logging.py

@@ -1953,6 +1953,7 @@ def test_reconnect(self):
 
         def recv_message():
             conn, _ = server.accept()
+            self.addCleanup(conn.close)
             chunk = conn.recv(4)
             slen = struct.unpack(">L", chunk)[0]
             chunk = b''